Technical ReportPDF Available

Renovation Cost-benefit Analysis Report

Authors:
Master Builders Centre, 1 Iron Knob Street (PO Box 1211), Fyshwick ACT 2609, Australia
Phone: (02) 6175 5915, Fax: (02) 6249 8374
Email: Energy.Partners@exemplary.com.au, Web: www.exemplary.com.au
A Division of Exemplary Investments Pty Ltd
ACN 111 635 931
ABN 83 111 635 931
Renovation Cost-Benefit Analysis
Report Prepared By
Energy Partners
July 2014
ENERGY
PARTNERS
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 2 of 99
1 TABLE OF CONTENTS
1. EXECUTIVE SUMMARY ............................................................................... 6
1.1 Energy Efficiency Measures: ....................................................................................... 6
1.1.1 Ceiling .................................................................................................................. 6
1.1.2 Roof ...................................................................................................................... 7
1.1.3 External Wall ........................................................................................................ 7
1.1.4 Subfloor ................................................................................................................ 7
1.1.5 Glazing ................................................................................................................. 7
1.1.6 Draught Proofing .................................................................................................. 8
1.1.7 Lighting Type ....................................................................................................... 8
1.1.8 All Energy Efficiency Measures Applied (All Measures Best Practice) ............. 8
1.2 Heating & Cooling Systems ........................................................................................ 9
1.3 Peak Load Analysis ..................................................................................................... 9
1.4 Comfort Analysis ......................................................................................................... 9
1.5 Health Analysis.......................................................................................................... 10
1.6 Hot Water Heating ..................................................................................................... 10
1.7 Solar PV ..................................................................................................................... 11
2. INTRODUCTION .......................................................................................... 12
2 METHODOLOGY ......................................................................................... 14
2.1 Base Renovation Models ........................................................................................... 14
2.2 Usage profiles ............................................................................................................ 15
2.2.1 Away During the Day ........................................................................................ 16
2.2.2 Someone Always at Home ................................................................................. 16
2.3 Climate Zones ............................................................................................................ 16
2.4 Orientation ................................................................................................................. 17
2.5 Energy Efficiency Measures ...................................................................................... 17
2.6 Measurement ............................................................................................................. 18
2.7 Energy Use ................................................................................................................ 18
2.8 Peak Load Analysis ................................................................................................... 18
2.9 Ductwork Efficiency .................................................................................................. 19
2.10 Comfort Analysis ................................................................................................... 20
2.11 Health Analysis ...................................................................................................... 20
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 3 of 99
2.12 Financial Savings ................................................................................................... 20
2.12.1 Building Fabric Improvements and Lighting Cost ............................................. 20
2.12.2 Heating Systems Cost ......................................................................................... 21
2.12.3 Cost Savings Per Annum .................................................................................... 24
2.13 Metered Energy Analysis ....................................................................................... 25
2.14 RatingOptimizer ..................................................................................................... 26
2.15 Quality Assurance .................................................................................................. 26
2.16 Energy Costs .......................................................................................................... 27
2.16.1 Seasonal Savings of Gas .................................................................................... 27
2.17 Solar Hot Water System ......................................................................................... 28
2.17.1 Gas Consumed By a Solar Hot Water System ................................................... 29
2.17.2 Performance in Northern Victorian compared to Southern Victoria ................. 29
2.17.3 6-Star Gas Instantaneous Water Heater Consumption ....................................... 30
2.17.4 Cost of Solar Water Heaters ............................................................................... 30
2.17.5 Cost of Gas Water Heaters ................................................................................. 31
2.17.6 Operating Life of Water Heaters ........................................................................ 31
2.17.7 Calculation of Annualised Cost .......................................................................... 32
2.17.8 Discount Rate ..................................................................................................... 32
2.17.9 Cost of Energy Saved ......................................................................................... 32
2.18 Performance of Solar Photovoltaic Systems .......................................................... 33
2.18.1 Electricity Consumption ..................................................................................... 33
2.18.2 System Size ........................................................................................................ 33
2.18.3 Performance Calculation .................................................................................... 34
2.18.4 Electricity Used On Site and Exported .............................................................. 34
2.18.5 Cost of PV System ............................................................................................. 35
2.18.6 Cost of Energy Saved ......................................................................................... 36
2.18.7 Annualised Costs/Benefits ................................................................................. 36
2.18.8 PV Output and Cooling Peak Load .................................................................... 36
3 RESULTS .................................................................................................... 37
3.1 Baseline ..................................................................................................................... 37
3.2 All Measures Best Practice ........................................................................................ 38
3.3 Lighting ..................................................................................................................... 39
3.4 Heating Systems ........................................................................................................ 40
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 4 of 99
3.5 Hot Water Systems .................................................................................................... 41
3.5.1 Annualised costs ................................................................................................. 42
3.5.2 Summary ............................................................................................................ 44
3.6 Solar PV Systems ...................................................................................................... 45
3.6.1 PV Generation across Victoria ........................................................................... 46
3.6.2 Cost of Energy Produced .................................................................................... 46
3.6.3 Annualised Costs/Benefits ................................................................................. 46
3.6.4 PV Output and Cooling Peak Load .................................................................... 47
3.6.5 Summary ............................................................................................................ 48
3.7 Building Fabric Improvements .................................................................................. 49
3.8 Peak Load Analysis ................................................................................................... 51
3.9 Comfort Analysis ....................................................................................................... 53
3.10 Health Analysis ...................................................................................................... 55
4 INTERPRETATION ...................................................................................... 56
4.1 General ....................................................................................................................... 56
4.2 Spreadsheets in a Workbook ..................................................................................... 57
5 CONCLUSIONS AND RECOMMENDATIONS ............................................ 59
5.1 Heat pumps and solar electric water heaters ............................................................. 59
5.2 Recommended Further Work .................................................................................... 60
6 ACKNOWLEDGEMENTS ............................................................................ 63
7 APPENDICES .............................................................................................. 64
7.1 Four Typologies ......................................................................................................... 64
7.1.1 Weatherboard cottage 1900s 1940s ................................................................. 64
7.1.2 Inter-war house 1920s 1940s ........................................................................... 64
7.1.3 Double fronted brick veneer 1960s 1970s ....................................................... 65
7.1.4 Estate style 1980s 1990s ................................................................................. 65
7.2 Definition of Baseline versions ................................................................................. 66
7.3 Definition Best Practice versions .............................................................................. 67
7.4 Usage Profile ............................................................................................................. 69
7.5 List of Indicative Simulations for Steady State Peak Heating and Cooling .............. 72
7.6 Solar Hot Water System analysis .............................................................................. 73
7.6.1 Gas Consumed By a Solar Hot Water System ................................................... 74
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 5 of 99
7.6.2 Performance in Northern Victorian compared to Southern Victoria ................. 76
7.6.3 6-Star Gas Instantaneous Water Heater Consumption ....................................... 76
7.6.4 Cost of Solar Water Heaters ............................................................................... 76
7.6.5 Cost of Gas Water Heaters ................................................................................. 77
7.6.6 Operating Life of Water Heaters ........................................................................ 77
7.6.7 Energy Costs ...................................................................................................... 78
7.6.8 Seasonal Savings of Gas .................................................................................... 79
7.6.9 Annualised Cost ................................................................................................. 79
7.6.10 Discount Rate ..................................................................................................... 81
7.6.11 Cost of Energy Saved ......................................................................................... 82
7.6.12 Results Table ...................................................................................................... 83
7.6.13 Summary ............................................................................................................ 84
7.7 Performance Analysis of Solar Photovoltaic Systems .............................................. 85
7.7.1 Electricity Consumption ..................................................................................... 85
7.7.2 System Size ........................................................................................................ 86
7.7.3 Performance Calculation .................................................................................... 86
7.7.4 Electricity Produced ........................................................................................... 87
7.7.5 Electricity Used On Site and Exported .............................................................. 88
7.7.6 Non-North Orientation ....................................................................................... 89
7.7.7 Cost of PV System ............................................................................................. 90
7.7.8 Cost of Energy Produced .................................................................................... 90
7.7.9 Annualised Costs/Benefits ................................................................................. 91
7.7.10 Results Table ...................................................................................................... 92
7.7.11 Summary ............................................................................................................ 93
8 NOTES ......................................................................................................... 94
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 6 of 99
1. Executive Summary
This report provides an analysis and evaluation of the impacts on energy, cost, health and
comfort benefits when 11 selected energy efficiency measures, which are of superior level
than the National Construction Code (NCC) minimum requirements, are applied to typical
house renovation projects in Victoria. Also the benefits from upgrading the heating/cooling
appliances, solar hot water and solar PV systems are evaluated. The NatHERS accredited
software AccuRate is used in this project for evaluating improvements to the construction of
the houses.
This simulation analysis was done for:
4 house typologies Pre-War, Inter-War, Double Fronted BV and Estate
4 orientations backyard facing N, S, E and W
3 climates - Mildura CZ4, Melbourne CZ6, Ballarat CZ7
2 occupancy patterns - Away during the day, Someone always home
2 heating and cooling scopes - ducted central and space heating only
2 heater and cooler efficiency levels - 3 star and 5 star
The results of almost 100,000 simulations are incorporated in an extensive smart Excel
Workbook which forms the basis of the planned interactive website to allow renovation
planners and customers to compare the options they have. The payback periods are all
calculated by comparing the capital costs and energy savings of the energy efficiency
measures relative to their NCC compliant alternative. As directed, in this report only the cost-
benefit of upgrading the heating system is analysed as almost all Victorian houses have some
type of heating system, not all of them have cooling appliances used in the house.
For this summary, selected results are reported below for their being indicative of common
trends. For consistency, all the results are for the average of all house types and orientations in
the Melbourne climate with:
occupancy pattern - Someone always home;
heating and cooling scopes - ducted central; and
heater and cooler efficiency levels - 3 star.
Here, for clarity of expression of its impact, each of the energy efficiency measures is applied
to the otherwise Baseline (NCC-compliant) version. Where some other result is seen as
worthy of citation, the associated details are explicitly stated.
1.1 Energy Efficiency Measures:
1.1.1 Ceiling
The NCC compliant ceiling insulation is R3.5 in the extension. R1.0 insulation is assumed to
have been already installed on the existing ceiling. The best practice ceiling insulation is R5.0
throughout the whole house. It would be unnecessary to remove the already-existing R1.0
ceiling insulation in the existing part during the renovation. The existing ceiling is
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 7 of 99
accordingly topped up to have a total of R6.0 insulation. The average payback in CZ6 is about
4 years.
1.1.2 Roof
Roof insulation is not required to comply with the NCC. The best practice roof insulation is
foil under R1.0 bulk insulation installed immediately beneath the roofing material. Cognisant
of the impracticality of retro-fitting it, this is applied to the extension part only.
On average the total cost of installation is the lowest but it is the least cost effective energy
efficiency measure. The average payback period is over 50 years (although its obvious
summer advantage is ignored in this study).
1.1.3 External Wall
The NCC compliant external wall insulation is R1.5 except the garage walls. Existing walls
are assumed to be uninsulated. The best practice version is to use R2.5 bulk wall insulation
with reflective foil in the extension and R2.5 bulk or cavity fill insulation in the existing
walls.
It is the most cost-effective of the energy efficiency measures. It has the greatest cost savings
per annum amongst the individual energy efficiency measures (i.e. excluding the scenario
where all energy efficiency measures are applied). The average payback period in CZ6 is 3.6
years. However the Inter-War typology has an average payback period of about 8 years due to
the more expensive process of installing cavity fill wall insulation to the existing double brick
walls for the modest added R1.0 insulation.
1.1.4 Subfloor
There are two main floor construction types used in the four typologies. The Pre-War, Inter-
War and the Double Fronted Brick Veneer typologies have enclosed suspended platform
timber floors. The Estate house has concrete slab on ground (CSOG) floor construction. The
NCC compliant platform floor insulation is R1.5 and Nil for the CSOG. Various floor
coverings are used according to the purpose of each room. For the best practice floor
insulation, the platform timber floors have R2.5 insulation. For the CSOG, R1.0 waffle pod
slab is used as the improved insulation. Floor coverings remain unchanged.
It is a cost effective energy measure which has the third lowest average payback period. The
average payback period for the insulation of the timber platform floors is about 2.6 years and
the CSOG is under 9 years.
1.1.5 Glazing
NCC2013 volume 2 glazing calculator was used to determine the NCC compliant and partial
compliance for glazing sizes. All the baseline house models use standard aluminium frame
with single glazing as the fenestration wherever partial compliance was acceptable. There are,
however, some cases in which clear double glazing in standard aluminium frames were used
to achieve an initial “pass”.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 8 of 99
Low-E Clear Glazing
This system returns the lowest average cost saving per annum and an average payback period
of over 100 years which is the highest amongst all the individually applied energy efficiency
measures scenarios, including the all measures best practice scenario.
Double Glaze with 12mm Air
This system provides an average payback period of over 75 years which is the second highest.
Double Glaze with Low-E 12mm Argon in Extension Only
This system provides an average payback period of 44 years
Double Glaze with Low-E 12mm Argon in Existing and Extension
This is the most expensive single energy efficiency measure (i.e. excluding the all measures
best practice scenario). The average payback period is 184 years, which is the highest,
amongst all the individually applied energy efficiency measures scenarios and including the
all measures best practice scenario
Double Glaze with Low-E 12mm Argon in Existing and Extension
This is the most expensive single energy efficiency measure (i.e. excluding the all measures
best practice scenario). The payback period is the lowest amongst all the glazing options used
in this study. The average payback period is 33 years.
1.1.6 Draught Proofing
This includes the installation of draught proofing around doors and windows, skirting boards
and above fans or fireplaces. Only the extension part of the renovation needs to be air sealed
to comply with the NCC. The best practice scenarios apply the above draught proofing
measures to both the existing rooms and extension. The average payback period is about 4
years.
1.1.7 Lighting Type
Vented downlights are acceptable but the modelling has to be compliant with the NCC to
allow the correct recognition of the infiltration. In the baseline extension there is one vented
downlight per 7m². For the best practice scenario, there are no vented downlights. Both
existing and extension light fittings are surface mounted LED.
The average payback period is about 7 years. Additionally, the average cost is the second
lowest.
1.1.8 All Energy Efficiency Measures Applied (All Measures Best Practice)
This scenario is equipped with all 7 improvements from above and the highest performing of
the fenestration improvements, the generic double glazed low-e argon-filled in improved
aluminium frames, is modelled in both the existing and extension windows.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 9 of 99
As expected the average heating and cooling energy demand is the lowest and thus the
average cost saving per annum of $3,766 is the highest. The average payback period is about
9 years.
1.2 Heating & Cooling Systems
The baseline scenario uses 3 stars ducted gas heating with add-on cooling systems. Ducts and
fittings (boots, spigots, etc.) insulation is NCC compliant at R1.0. The best practice scenario
upgrades the 3 stars systems to 5 stars and the ducts insulation to foil-sleeved R1.5. The
additional average cost for this upgrade is about $1,000 and the payback period is under about
1 year.
1.3 Peak Load Analysis
The hourly energy demands from the AccuRate simulations are converted to energy
consumptions to establish the impact on appliance size and demand on the electricity grid and
gas supply (metered energy). A total of 96 simulations consisting of 48 Baselines and 48 All
Measures Best Practice were chosen for this analysis. Below is a summary of the results
indicating that the Peak Load is reduced by a similar fraction to the annual energy:
Steady State
Peak
Gas Heating
(MJ/h)
Steady State Peak
Electrical Cooling
(kW)
Total Metered
Energy
Heating
(MJ/yr)
Total Metered
Energy
Cooling
(kWh/yr)
Baseline
60
3
80,381
456
All Measures Best Practice
11
1
14,063
136
Difference
-82%
-71%
-83%
-70%
Table 1 Peak load analysis summary for CZ6
1.4 Comfort Analysis
This is a measurement (in Degree.Hours per year) of the capacity of the building envelope to
maintain a comfort range between18°C and 23°C when no heating or cooling is operated to
condition the house. The same set of 96 simulations used in the peak load analysis is
simulated with no heating and cooling applied. Daytime zones and night-time zones are
analysed separately to provide more detailed results.
A higher Degree.Hours means the house is less efficacious in maintaining the internal
temperature within the comfort range without heating or cooling. Table 2 provides a summary
of the results. The greater -ve % values indicate that the all measures best practice is superior
to the baseline.
This method allowed for the maximum and minimum indoor temperatures to be determined.
The average differences between the baseline and the all measures best practice are
summarised in Table 3:
The all measures best practice has a lower maximum (cooler) and higher minimum (warmer)
indoor temperature when the house is not conditioned.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 10 of 99
Average Degree.Hours
Daytime
Cooling
Daytime
Heating
Night-Time
Cooling
Night-Time
Heating
2,307
21,293
2,763
22,089
2,034
10,163
2,326
10,607
-12%
-52%
-16%
-52%
Table 2 Average Degree.Hours for the comfort analysis in CZ6
Average indoor temperature (°C)
Daytime
Max.
Daytime
Min.
Night-time
Max.
Night-time
Min.
Baseline
35.3
6.7
36.1
6.1
All Measures Best Practice
34.2
10.3
34.2
10.0
Difference
-1.1
3.6
-1.8
4.0
Table 3 Average maximum and minimum indoor temperatures from the comfort analysis in CZ6
1.5 Health Analysis
Similar to the comfort analysis, this method measures the hours per year when the internal
temperature exceeded a much wider tolerable (healthy) range from 13°C to 30°C. Below is a
summary of the average Degree.Hours. . The table below provides a summary of the average
degree heating and cooling hours.
Average Degree.Hours
Daytime
Cooling
Daytime
Heating
Night-
Time
Cooling
Night-
Time
Heating
Baseline
130
3,489
184
3,920
All Measures Best Practice
84
541
92
557
Difference (%)
-35%
-84%
-50%
-86%
Table 4 Average degree.hours for the health analysis in CZ6
1.6 Hot Water Heating
An analysis of water heating options has been undertaken. This compared the financial
benefits of solar and high efficiency gas water heaters with a standard efficiency gas water
heater that is the likely default product installed.
The money a householder needs to invest to save a MJ of gas is equivalent to, or less than, the
current cost of gas for both a gas boosted solar water heater and a six star instantaneous gas
water heater when compared to a four star gas water heater. These options are always less
expensive in homes where there are three or more occupants.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 11 of 99
Cost of energy saved $/MJ
Comparison of water heating with the four star gas storage water heater
Occupants
1
2
3
4
5
6
7
8
Solar with
Gas
Boosting
Regional-South
0.015
0.013
0.012
0.011
0.010
0.010
0.009
0.009
Regional-North
0.013
0.012
0.010
0.009
0.009
0.008
0.008
0.008
Metro
0.015
0.013
0.012
0.011
0.010
0.010
0.009
0.009
Mildura
0.013
0.012
0.010
0.009
0.009
0.008
0.008
0.008
6 Star Instantaneous Gas
0.007
0.007
0.007
0.007
0.006
0.006
0.006
0.006
Table 5 Cost of energy saved $/MJ compared to four star gas storage water heaters
Based on annualised costs, gas boosted solar water heaters are always the most cost effective
option.
1.7 Solar PV
The option to install a solar electricity system, a photovoltaic (PV) system at the time of
renovation has been investigated to understand the financial opportunity that arises.
With current electricity tariffs and feed in tariffs the most cost effective option is to size a PV
system so that most of the electricity it produces is used on site.
A 1.5 kW system will save the household $200 to $480 annually over its operating life
including paying for the purchase and installation price. Annualised Savings are given in
Table 6Table 24:
Occupants
1
2
3
4
5
6
7
8
Load kWh/yr
3886
4808
5691
6613
7526
8440
9355
10253
Annualised
$/year
Tullamarine
$207
$237
$263
$287
$ 309
$328
$344
$358
Ballarat
$ 243
$278
$308
$335
$360
$381
$399
$413
Mildura
$ 275
$314
$349
$383
$414
$442
$466
$ 486
Melbourne
$ 180
$207
$230
$252
$272
$288
$303
$314
Table 6 - Annualised savings by location and Household size/load
The money a householder needs to invest to save a kWh of electricity is significantly less than
the current cost of electricity: 6-9 c/kWh compared to 27-30 c/kWh to purchase electricity
from the grid.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 12 of 99
2. Introduction
The client for this project is Sustainability Victoria.
The aim of this work was to develop heating and cooling data for a range of renovation case
studies of four (4) typical Victorian house styles, using Nationwide House Energy Rating
Scheme (NatHERS) accredited software to undertake thermal modelling for each house style
in a number of different climate zones. The data from the thermal modelling is combined with
data on heating and cooling system type and efficiency, to estimate the energy savings from
upgrading the building shell and heating/cooling equipment. Additionally, modelling of
different lighting and water heating options, as well as other solar options (e.g. solar PV
panels and solar water heating) was undertaken to assess the potential costs and benefits of
these upgrades in three (3) indicative Victorian climates.
This data has formed the technical measurement of energy, cost, health and comfort benefits
that can be achieved by going beyond minimum National Construction Code (NCC)
requirements and implementing best practice energy efficiency measures. These energy, cost,
health and comfort benefits will be used in the development of a customisable online tool for
Victorian home renovators.
The typical renovations modelled in this study capture key design features and enhancements
that are common in renovations. The Victorian Building Commission’s recent work to
characterise the renovation market in Victoria from 2009 to 2011 provides some guidelines
for typical improvements:
The majority of home renovations involved demolishing rear kitchen, laundry,
bathroom areas and their replacement with a large new open plan combined
kitchen/living/dining area and new laundry and bathroom/WC areas. These new open
plan kitchen/living areas opened onto new decks and other outdoor living spaces.
The main trends in refurbishment of existing floor areas included; adding robes in
existing bedrooms, refurbishing bathrooms, creating ensuites, converting existing
kitchen areas into bathrooms/laundries, converting bedrooms into lounge/rumpus areas
and creating open plan kitchen/living/dining areas by breaking down internal walls.
Common trends in first floor additions included addition of bedrooms and bathrooms.
The most common construction types in new additions were mainly:
Wall construction was mainly weatherboard or brick veneer. External foam board
cladding was prevalent in upper floor additions.
Floor constructions were mainly timber platform floors on concrete stumps or concrete
slab on ground.
Roofing materials were predominantly formed sheet-metal or concrete/clay tiles.
Generally, the construction materials of the new additions were selected to maintain a
visual similarity with the existing parts of the home.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 13 of 99
The energy efficiency measures modelled in this study were finalised in consultation with
Sustainability Victoria at the contract inception meeting with some subsequent refinement to
that (see Table 30 and Table 31).
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 14 of 99
2 Methodology
2.1 Base Renovation Models
The team accessed designs and drawings for four (4) renovation case studies prepared by
Sustainability Victoria, with input from the Archicentre enterprise of the Australian Institute
of Architects. The case study houses were chosen based on construction typologies that
contain common Victorian building elements and have the greatest impact to improve the
existing housing stock (based on ABS data), as described in the table below.
The base renovation models contain typical house plans and room sizes of the era plus a
typical renovation for that style of house. The thermal modelling for these house plans was
undertaken by Energy Partners using NatHERS software. The heating and cooling outputs
from the NatHERS thermal modelling provided the baseline data for measuring the impact of
the ten (10) selected energy efficiency improvements, (see Appendix Definition Best Practice
versions).
The renovations were modelled to meet minimum standards according to the NCC 2013 to
form the Baseline data (see Appendix Section 7.2 for details) and for comparison with the
Best Practice alternatives.
Case studies
Typology
Age range
Construction
elements
Typical
renovation
1
Lightweight
construction,
timber floors
Weatherboard
cottage
(Pre-War)
1900s - 1940s
Timber framed walls,
timber framed floors
on stumps, timber
windows, tiled roof
Internal
alterations, rear
extension
2
Heavy weight
construction,
timber floors
Inter-war house
(Inter-War)
1920s 1940s
Double brick walls,
timber windows.
Timber framed floor
on stumps, tiled roof
Internal
alterations, upper
and rear extension
3
Middleweight
construction,
timber floors
Double fronted
brick veneer
(DFBV)
1960s 1970s
Brick veneer walls,
timber framed floor,
metal framed
windows, tiled roof
Internal
alterations, rear
extension
4
Middleweight
construction,
concrete slab
floors
Estate style
(Estate)
1980s 1990s
Brick veneer walls,
concrete slab on
ground, aluminium
windows, metal roof
Internal
alterations, upper
and rear extension
Table 7 Case Studies of typical renovations - their typology, age range and construction
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 15 of 99
Total Floor
Area (m²)
Conditioned Floor Area (m²)
Total Floor Area
Existing Floor
Area
Extension Floor
Area
Pre-War
206
192
136
56
Inter-War
180
156
92
64
DFBV
176
152
108
44
Estate
184
162
107
55
Table 8 Gross floor areas of the 4 typologies modelled in this study
2.2 Usage profiles
The NatHERS software applies a standard usage profile for the heating and cooling systems
when calculating the thermal loads within the houses. For living spaces, thermal comfort is
maintained from 7 am to midnight. For sleeping spaces, thermal comfort is maintained from 4
pm to 9 am the following morning. The software makes no provision for Daylight Saving so
all times are Standard Times, including the occupancy patterns and the internal loads
associated with them.
For the heating thermostat, the following rules are applied to all the house models:
For living spaces (including kitchens and other spaces typically used during waking
hours): a heating thermostat setting of 20°C is applied.
For sleeping spaces (including bedrooms and other spaces closely associated with
bedrooms): a heating thermostat setting of 18°C is used from 7 am to 9 am and from 4
pm to midnight; and a heating setting of 15° C from midnight to 7 am the following
morning.
For the cooling thermostat, different settings are applied to different climate zones in
recognition of acclimatisation. In NatHERS software tools there are 69 climate zones (which
are subdivisions of the 8 NCC climate zones). Table 9 lists the 3 selected climate zones and
their corresponding cooling thermostat settings.
NCC
Climate Zone
NatHERS
Climate Zone
Cooling Thermostat Settings
Mildura
4
27
25.0
Tullamarine
6
60
24.0
Ballarat
7
66
23.5
Table 9 Cooling thermostat settings for each selected NatHERS climate zone
Rather than using the NatHERS assumed profiles, this study explores 2 different usage
profiles based on more typical usage patterns for residential heating and cooling systems, as
this allows a more accurate estimate of the likely actual heating and cooling loads. Two
general profiles were used:
1. Away during the day; and,
2. Someone always at home.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 16 of 99
Appendix Section 7.4 shows the usage profile example of the Double fronted brick veneer
typology in CZ6 which compares the standard NatHERS settings for living, living/kitchen and
bedroom with both the “Away during the day and “Someone always at home” profiles
modelled in this study.
2.2.1 Away During the Day
It is assumed that there are no occupants in the house from 9 am to 6 pm.
For Living and Bedroom zones, both sensible and latent internal heat loads from 9am to 6pm
are set to 0. Similarly the cooling and heating thermostats for hours from 9am to 6pm are set
to “off” (thermostat set to 0 in a scratch file means that at those hours the zone is not
conditioned).
In general, on cold mornings people will turn the heating on, however on hot mornings the
cooling is not turned on. The heating thermostats from 7am to 9am are set to be “on” while
the cooling thermostat is set to be “off”.
For Kitchen & Family zones, internal sensible heat load is set to the background value of
100W. This value represents consumptions from appliances which are always “on” (e.g.
fridge). Internal latent heat load is 0 and the thermostats are set to “off” from 9am to 6pm.
For other living zones, there are no internal heat loads as in the NatHERS standard. The
thermostat settings are the same as above.
2.2.2 Someone Always at Home
The NatHERS standard schedule assumes the Living, Kitchen, Family and other living areas
are always occupied, even when not conditioned. No modification is made neither to the
internal heat loads nor the thermostat settings.
For Bedrooms, the NatHERS standard schedule assumes no occupant in the bedrooms during
the day. To represent a full day occupancy pattern, both the sensible and latent internal heat
loads during the daytime hours are assumed to be the same as the evening hours in the
NatHERS standard schedule. For the thermostat settings, both heating and cooling thermostats
at 8 am and 9 am in the NatHERS standard schedule are extended to the rest of the day to
represent a full day occupancy pattern. The thermostats in these 2 hours are higher than the
hours before 7 am. This assumes the occupants are awake and having normal “household
activity” in the house.
2.3 Climate Zones
The NatHERS modelling was undertaken for the 4 house styles modelled using three
Victorian climate zones that are representative of hot, mild and cold climates:
1. Hot: Mildura NatHERS No. 27 - indicative of NNC CZ 4
2. Mild: Tullamarine (Melbourne) - NatHERS No. 60 - indicative of NNC CZ 6
3. Cold: Ballarat NatHERS No. 66 - indicative of NNC CZ 7
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 17 of 99
2.4 Orientation
The NatHERS modelling assessed the effect of orientation on the heating and cooling loads of
the 4 house styles modelled. Modelling was undertaken over the four cardinal orientations:
north, south, east and west facing rear yards.
2.5 Energy Efficiency Measures
A range of energy efficiency measures were modelled to measure their impact against the
minimum energy efficiency requirements as prescribed in the NCC 2013 or MEPS and can be
categorised into:
1. Building fabric improvements;
i. Insulation (ceiling, walls and floors to best practice standards)
ii. Glazing (including orientation and shading)
iii. Full draught proofing measures
2. Lighting use of downlights (QH and LED) compared to minimal use of downlights
3. Heating & Cooling
4. Hot water systems
5. Photovoltaic (Solar PV) systems to generate electricity on-site
See Appendix Section 7.2 and 7.3 for full list of energy efficiency measures applied to the
Baseline and Best Practice models.
The analysis assesses building fabric energy efficiency improvements 1) and 2) individually
and simulates them in NatHERS software. The heating and cooling load outputs are inserted
into a spreadsheet tool developed for this project.
Once the thermal simulations were completed the benefits of upgrading 3) heating & cooling
and 4) hot water systems, as well as 5) solar systems were analysed.
The modelling demonstrates the effects of two types of heating systems:
1. Space heating, i.e. heating the main living areas only; and
2. Central heating, i.e. heating both the living and bedroom areas.
The effects of zoning the heating systems is measured in the best-practice renovation models,
by selected sample versions being modelled in both modes with both occupancy profiles. The
proportionalities inferred from that work is applied to the other results as estimation factors
for that house type. This aspect is particularly relevant between the ground floor and any
upper floor of the house, but all examples in this project are single storey.
The analysis also assesses and quantifies the benefits of the following upgrades:
3. Ducted gas heating system
4. Gas boosted solar hot water
a
5. Gas hot water
6. solar PV (photovoltaics) to generate on-site electricity
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 18 of 99
2.6 Measurement
The results of simulating both 1) building fabric improvements and 2) lighting upgrades were
collected in a spreadsheet tool designed for the project and used for further analysis. The
annual heating and cooling outputs from NatHERS are measured in MJ/m². The out-put
energy values were multiplied by the net conditioned area of the house (m
2
), to calculate the
total annual heating and cooling load in MJ.
The calculated MJ/m² and its conversion to % improvement allows for customised data to be
drawn upon by the online tool for renovators. The energy efficiency measures are assessed
individually, however when the data is developed by SV into an online tool there are inter-
dependencies between the measures. These possible dependency scenarios and solutions for
estimating the total benefits of multiple measures were to be addressed in the detailed analysis
by interpreting them in their % improvement measures. Instead, the project scope was
expanded to include most combinations of interest directly using highly automated simulation
techniques including just under 100,000 EEM combinations.
2.7 Energy Use
It is important to note that the thermal loads calculated using the NatHERS software are not
the same as the actual heating and cooling energy use of the houses. They are simply the heat
energy input required to maintain the specified thermal comfort conditions during the ‘winter’
months and the heat energy which needs to be extracted from the house to maintain the
specified thermal comfort conditioners during the ‘summer’ months. Metered energy is
subsequently calculated. For details please refer to Section 2.13 Metered Energy Analysis.
The heat load outputs for different types of heating (space/central), cooling and different
heating/cooling usage profiles (all day / away day) was combined with data on typical
heater/cooler performance to estimate the annual energy use.
2.8 Peak Load Analysis
The hour-by-hour energy results from AccuRate are used to establish the impact on appliance
size and demand on the electricity grid.
A total of 96 simulations consisting of 48 Baselines and 48 All Measures Best Practice
(equipped with all 7 improvements and the highest performing of the fenestration
improvements Generic DG Low-e argon in improved Aluminium frame to both existing and
extension windows) were chosen for this analysis. Central heating mode and “Someone
always at home” usage profile are used in these simulations.
The heating and cooling energy outputs from the AccuRate simulations are energy demands
rather than energy consumptions. To calculate the energy consumptions the following heating
and cooling systems are used:
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 19 of 99
Baseline: The ducts and fittings (boots, spigots, etc.) insulation are NCC compliant
(R1.0) with a 3 star gas heater. The efficiency of a 3 stars
b
gas heater is 60% (at
standard conditions) and the minimum rated EER for a 3 stars cooling system is 3.75.
c
All Measures Best Practice: 5 stars heater (90% efficiency) and 5 stars cooling
(minimum rated EER of 4.75) with foil-sleeved R1.5 ducts zoned.
Both the Baseline and the All Measures Best Practice systems are deemed to have negligible
air leakage in operation such that all detrimental heat flow into and out of the ducts is through
the insulated duct and fitting walls. Older installations could well have some air leakage but
this should be made good during the renovation project if the system is not being replaced.
Quasi Steady State Peaks During the daily start up hours the conditioned spaces could
begin at an extremely high or low temperature. The peak loads of these hours are not suitable
to be used for sizing the air-conditioning system or estimating its impact on the electricity and
gas distribution grids
d
. Instead, the steady state peaks, which are calculated by Exemplary
NatHERS Analyzer, excluding the start-up hours, are used for sizing the heating and air-
conditioning systems. Hours excluded in the peak load calculation for the Away during the
day occupancy are the hours ending at 8 am and 5 pm. These are the first after start up hours
for heating on a cold morning and cooling during/after a hot afternoon and may be
misleadingly large, especially in the case of heavyweight constructions. For the “Always
home” occupancy, the hours which needed to be excluded in the calculations are different.
Only the hours ending at 8 am will be excluded in the calculation because the house is
conditioned continuously and does not have a start-up hour in the afternoon.
Thermostat settings are scheduled in Appendix Section 7.4 for the NatHERS Standard and the
two occupancy patterns used for this project.
With the heat or cool demand and the hour at which they occur identified, the COP of the
heater and/or cooler at the coincident outdoor air temperature is applied to the demand to
calculate the metered energy peak load for the whole year.
2.9 Ductwork Efficiency
A duct plan for the central heater/cooler is schematically designed for each house as extended
to establish a schedule of duct and fitting sizes (diameters) and lengths from which the area of
duct wall facing up, down and sideways can be calculated along with the overall heat
loss/gain coefficient (W/K). Any return air duct was assumed to run inside the conditioned
space with negligible heat losses/gains and is hence ignored in this calculation. For the
Baseline case, it was assumed that new ducts were installed throughout the whole house and
the ductwork insulation complies with the minimum requirement of the NCC 2013
e
. Table
3.12.5.2 of Section 3.12.5.3 of the NCC 2013 Volume Two states the minimum ductwork
insulation for climate zones 4, 6 and 7 is R1.0 (with a non-foil sleeve) for a heating only
system where the ductwork was assumed to be located in the roof space, above any ceiling
insulation and below any roof level foil or insulation. (The notes to that table allow a
reduction by R0.5 for ducts run in the more moderate environment of under an enclosed
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 20 of 99
suspended timber floor, but evaluating that option in the Typologies where it might be
applicable is beyond the scope of this project.
f
)
2.10 Comfort Analysis
This is a calculation of the degree.hours per year when the internal thermal comfort range of
18°C to 23°C is not exceeded during and unconditioned mode of operation. This allows
renovators to see the comfort benefits of energy efficiency measures.
The same set of 96 simulations used for the peak load analysis is simulated with no heating
and cooling applied (both thermostats are set to 0 in the scratch file).
Comfort improvements will not apply to all energy efficiency measures (e.g. water heating
and solar PV have no comfort impacts).
2.11 Health Analysis
This is a calculation of the degree.hours per year when the internal thermal conditions remain
within the tolerable range of 13°C 30°C.
Similar to the comfort analysis, the same set of 96 simulations used for the peak load analysis
is simulated with no heating and cooling applied (both thermostats are set to 0 in the scratch
file).
Each selected simulation generates a file of hourly internal temperatures by room and the
hourly average of these temperatures for the daytime zones and night-time zones are
separately analysed to find the maximum and minimum temperatures incurred, the number of
hours outside the tolerable range and the degree.hours outside the tolerable range are
calculated so that a robust estimate of the health-threatening discomfort can be inferred
2.12 Financial Savings
Financial savings are represented as the dollar savings per annum for each of the best practice
building fabric improvements compared to the Baseline figures, and the resultant payback
periods were calculated using the differential cost.. The financial analysis (e.g. costs vs
savings) is split into (1) building fabric improvements; (2) lighting; (3) heating systems (the
financial savings for upgrading the cooling system are not calculated in this report); and (4)
water heating and (5) solar.
2.12.1 Building Fabric Improvements and Lighting Cost
Table 10 shows the capital costs associated with improving the building fabric. These prices
are for reference only and they varied between locations and time of supply.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 21 of 99
Price
g
Included GST &
Installation
Ceiling
R3.5
$15.40
/m²
R5.0
$20.50
/m²
Roof
R1.0 + Foil
$12.50
/m²
Wall
R1.0 (Cavity fill)
$37.00
/m²
R1.5
$12.20
/m²
R2.5 (90mm Batts) + Foil
$18.30
/m²
R2.5 (90mm Batts)
$16.30
/m²
R2.5 (Cavity fill)
$37.00
/m²
Floors*
R1.5 (sub-floors)
$17.90
/m²
R2.5 (sub-floors)
$17.90
/m²
R1.0 (CSOG)
$17.90
/m²
Draught
Proofing
Doors
$101.00
/unit
Windows
$102.00
/unit
Skirting boards
$10.20
/m
Exhaust fan
$67.20
/unit
Fireplace
$254.70
/unit
Lighting
Incandescent Downlights (commonly 12 volts)
$5.10
/unit
LED (unvented)
h
$122.00
/unit
Glazing
SG Standard Aluminium
$350.00
/m²
Low-e Standard Aluminium
$420.00
/m²
DG clear (12mm Air) Standard Aluminium
$454.00
/m²
DG Low-e (12mm Argon) Standard Aluminium
$558.00
/m²
DG Low-e (12mm Argon) Improved Aluminium Frame
$687.00
/m²
*The price (materials only) for the two subfloor insulations R1.5 and R2.5 Glasswool are about the same. The
installation of sub-floor insulation in an existing house involves working in an unpleasant environment (i.e.
crawling under the timber floor) and so the labour costs make the material cost difference appear to be
negligible. The material cost of R1.0 (extruded polystyrene) for CSOG is more expensive than the Glasswool but
the installation involves much less labourintensive work. The prices including installation for the sub-floor or
the CSOG insulation are about the same.
Table 10 Building Fabric Improvements Cost
2.12.2 Heating Systems Cost
The heating systems cost are calculated based on the peak loads and the type of system. A
ducted gas heating system is used for the central heating scenario. For the space heating
scenario, the house will be heated by a two-way flued gas wall furnace.
System sizes come in a modest range which varies between manufacturers and over time,
slowly responding to a gradual increase in house size but an increasing energy efficiency of
the building envelope. While the estimated actual cost varies in response to design loads
necessarily in a rough step function, we have developed an equivalent linear function for each
case based on the ranges currently available.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 22 of 99
Central Heating
System sizes and their corresponding costs are available from the Rawlinsons
i
Handbook.
However the data does not include the appliances star rating. The costs are the total price of
provision and installation of ducted heating systems. Also the cooling and heating size
combination does not match any system consistent with our simulation results (see Section
3.8) as the minimum cooling/heating system listed by Rawlinsons is 25 kW.
To find the relationship between star rating, cost and system size, additional information was
provided by the ActewAGL energy shop
j
and the Gstore
k
website. Data are plotted in Figure
1. Note that the prices in the figure exclude installation costs.
Figure 1 Cost, Size and Star Rating of the Ducted Gas Heating System
We have assumed systems in any sizes are available to demonstrate the theoretical cost
differences between using a lower and higher star-rating appliances.
The following two equations are obtained from the above figures and they are used to
estimate the cost of the 3 and 5 Star air conditioning system for the central heating scenario.
Gas Heating:
5 Stars:
1440461.38)( kWPeakGasHeatingCost
3 Stars:
70031)( kWPeakGasHeatingCost
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 23 of 99
Space Heating
Costs and star rating for the gas space heater are also obtained from Gstore website and are
plotted in Figure 2.
Figure 2 Cost, Size and Star Rating of the Gas Space Heater
Similar to the ducted gas heating system, we have assumed systems in any sizes are available.
The equations below are used to estimate the cost of the 3 Star and 5 Star air conditioning
systems for the space heating scenario:
Gas Heating:
l
5 Stars:
500170)( kWPeakGasHeatingCost
3 Stars:
400130)( kWPeakGasHeatingCost
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 24 of 99
2.12.3 Cost Savings Per Annum
The cost saving per annum is the cost difference between the energy cost of Baseline and Best
Practice approaches (with selected energy efficiency measures applied). As requested by SV,
the cost savings per annum for heating are calculated for the following 2 scenarios:
1 Using 3 Star heating systems.
2 Upgrade the 3 Star systems to 5 Stars.
A 3 Star heating system is always assumed to be used in the Baseline cases.
m
Using 3 Star systems:
Both Baseline and Best Practice are using 3 Star systems. Therefore the annual cost saving is
a result of the improvement in building fabric alone.
Upgrade the 3 Stars systems to 5 Stars
n
:
Same as above but the Best Practice has a 5 Star heating system. The annual cost saving is a
result of the building fabric improvement plus the saving of using a more efficient heating
system.
The energy cost is calculated by multiplying the heating metered energy by the gas/electricity
energy cost. The total metered energy is the energy consumption of the heating systems. It is
calculated by adding up the hourly energy demands and the hourly energy losses/gains in the
ducts.
SavingPerAnnum3Star = (GasHeatEnergyBaseline * GasPrice / 100) - (GasHeatEnergy3Star
* GasPrice / 100)
SavingPerAnnum5Star = (GasHeatEnergyBaseline * GasPrice / 100) - (GasHeatEnergy5Star
* GasPrice / 100)
Ductwork and Installation Cost
During the upgrade of the heating system, the house owner may want to keep the existing duct
system and put new ductwork in the extension only. However some of the existing ducts may
need to be replaced due to leakage and general wear of the old ducts and for the new heating
system to run better with the extra duct length within the extension. We have assumed new
ductwork is needed throughout the whole house for a better estimation of the maximum cost
needed.
The estimated cost for the R1.0 ductwork is $1200 and we assume the same price for the four
typologies. For the R1.5 ductwork it is an extra of $60 per outlet
o
.
The installation cost of the ducted gas system is assumed to be the same regardless of the
system size, $1800. The installation cost (replacing an existing) of the gas space heater is
$200.
Below is the ductwork and installation cost summary for the ducted gas heating system:
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 25 of 99
Estimated
installation cost
for the gas
furnace
Estimated cost for ductwork
Total Installation
Cost
3 stars with
R1.0 duct
$1,800
$1,200
$3,000
5 stars with
R1.5 duct
$1,800
$1200 + $60 per outlet for the R1.5
ductwork.
Below are the number of outlets and
extra cost for the R1.5 ductwork:
PreWar: 3 = $180
InterWar: 4 = $240
DFBV: 5 = $300
Estate: 2 = $120
$3120 - $3300
2.13 Metered Energy Analysis
NatHERS software estimates the heat energy input (or heat energy required to be removed) to
meet specified thermal comfort conditions in winter and summer it does not estimate the
actual metered energy consumption for a house as this also depends on the conversion
efficiency of any heating and cooling appliances and also the thermal efficiency of any
ductwork and fittings used with ducted systems. However, these are non-building aspects that
impinge on the energy efficiency of the house as a comfort conditioned system. To evaluate
their significance, the metered energy consumptions are calculated using the Exemplary
NatHERS Analyser
p
. It estimates the metered energy consumptions of the NatHERS-
calculated heating and cooling demands. Hourly calculations apply temperature-appropriate
efficiencies called Coefficients of Performance (COPs). This is where the “efficiency” of the
heating or cooling system is greater than a unit of one and is indicated by the star-rated
efficiency of the appliances and associated duct heat loss/gains wherever they are located.
Hour-by-hour calculations based on selected output files from the simulations, which record
the hourly loads and temperatures within each room, were undertaken. The peak load from all
of the non-start-up hours for heating and cooling was extracted from the AccuRate results and
later used to calculate duct losses/gains by tallying the loads for all the rooms and expressing
that as a fraction of the peak load. Hence, the temperature for any particular hour inside the
duct is a function of the load during that hour and in the range 20-35°C for heating and 14-
25°C for cooling.
The appliance energy conversion efficiency (or Coefficient Of Performance, COP), varies
subject to outside air temperature for some heating/cooling appliances. This can cause a
Reverse Cycle Air Conditioner (RCAC) or Heat Pump to be more efficient when the outside
air is close to the comfort temperature and the efficiency declines as that temperature moves
toward the extremes. That function, generalised from the values published by ASHRAE
q
and
scaled to ensure that the Star-rated COPs coincide at the standard rating temperatures
(Heating = 8°C and Cooling 35°C), was then fitted to the hour-by-hour total of rooms-plus-
ducts loads to estimate the annual consumption and also the annual average COP for cooling.
The efficiency of the gas furnace is largely independent of ambient temperature so this
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 26 of 99
technique is not required for the heating energy in this project but the incorporation of RCACs
in the proposed website would be a worthwhile extension of this project.
This process converts the AccuRate results to metered energy values in kWh for cooling and
MJ for heating.
Figure 3 Inferred heating and cooling COP vs Ambient temperature
2.14 RatingOptimizer
RatingOptimizer is another proprietary software developed by Energy Partners. This software
has the following functions:
Reads in SCRATCH files generated by AccuRate and applied energy efficiency
measures to the house model.
Batch runs to do large-volume simulation automatically.
Calculates degree.hours according to the user-defined tolerable range.
2.15 Quality Assurance
To ensure the quality of the simulations and calculations, the following precautions are
carried out:
Manual checking of the SCRATCH files to ensure the modifications made by
RatingOptimizer are correct.
SCRATCH files generated by RatingOptimizer are also compared with those
generated by AccuRate to ensure the energy measures are applied correctly.
The health data results are checked by doing manual calculations and compared with
the results generated by the Rating Optimizer.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 27 of 99
2.16 Energy Costs
Energy prices vary across the state and vary by time of use.
Gas has seasonally adjusted peak and off peak seasonally and electricity is consumed
predominantly as a single or two stage tariffs. For this analysis the marginal energy prices
produced by Energy Consult for SV in 2013 have been used. Electricity prices have been
increased by 3.7% and gas prices have been increased by 4.9% to account for recent price
changes.
The energy saved by implementing the measures in this study are costed at the marginal
prices relevant for the times that the technologies are active.
The marginal cost of electricity on a single rate tariff is the average electricity price. This is
27.48 cents/kWh for Metropolitan areas and 29.96 cents/kWh for Regional Victoria.
Gas prices are more complex as there are a number of price steps, which are different in peak
periods of June to October than the non-peak periods. Consequently, the marginal prices vary
depending on seasonal use profile and the amount of gas used. EnergyConsult has provided
marginal gas prices for small, medium and large gas using households. The marginal gas
prices are given in Table 11 below, updated to 2014.
Metropolitan
Regional Vic
Mildura
Small
Medium
Large
Small
Medium
Large
Average Marginal Winter
c/MJ
1.70
1.47
1.47
1.79
1.60
1.60
2.69
Average Marginal Summer
c/MJ
1.81
1.54
1.49
1.80
1.62
1.62
3.45
Solar savings Price
c/MJ
1.77
1.52
1.48
1.80
1.61
1.61
3.22
Gas* savings price
c/MJ
1.75
1.51
1.48
1.80
1.61
1.61
3.07
Gas saved at the average of summer and winter marginal rates
Table 11 Marginal gas prices 2014 by household size and region (after EnergyConsult 2013)
The gas prices in Mildura are different from the rest of Victoria in that there is no change
between summer and winter.
For this analysis, households of
1 and 2 persons will use the prices for Small,
3 persons - the mean of Small and Medium marginal prices,
4 and 5 persons - Medium prices and
6 or more person households - Large prices.
2.16.1 Seasonal Savings of Gas
As gas prices vary seasonally (peak prices are from 1 June to 30 October) reduction in gas
consumption resulting from solar boosted water heaters across the seasons is required to
evaluate savings. The savings will predominantly occur in summer resulting in a 70% savings
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 28 of 99
during off peak months and 30% saving during peak months. Therefore, the marginal savings
for a solar boosted gas water heater will be 70% ‘summer prices and 30% winter prices
(shown in Table 11 above).
Gas saved by using the more efficient 5 star gas water heater will be at the average of the
marginal summer and winter prices. (See Table 11)
2.17 Solar Hot Water System
In order to understand the savings to be made when installing a solar water heater or a 5 star
gas water heater the amount of hot water used for households of different sizes is needed.
There exists a range of discussions in the literature but there is no clear method.
A model of hot water use based on the levels specified in AS/NZS 4234 was developed. The
model is linear with consumption varying proportionally with occupancy, as listed in Table
12.
Number of
occupants
r
1
2
3
4
5
6
7
8
HW litres
Raised by 45K
65
99
133
167
201
235
269
303
Q
ave
MJ/day
12.3
18.7
25.1
31.6
38.0
44.4
50.8
57.3
Q
peak
s
MJ/day
13.6
20.7
27.8
34.9
42.0
49.1
56.2
63.3
Table 12 Hot water consumption vs occupant number (consumption in Litres, Average Energy per day and in Peak Energy
per day)
The water heater most likely to be installed in a Victorian home by a builder is a four star gas
storage water heater. The calculation of the Annual Energy Saving using AS/NZS 4234 is
based on a comparison with a three star gas water heater. Consequently, for this analysis the
Annual Energy Consumption for both three star and four star gas water heaters are required.
The Annual Energy Consumption (A
E
) of gas storage water heaters is given in Table 13.
Occupants
1
2
3
4
5
6
7
8
Hot water
consumption
litres/day
65
99
133
167
201
235
269
303
MJ/day
12.3
18.7
25.2
31.6
38.0
44.4
50.9
57.3
MJ/year
4,489
6,837
9,186
11,535
13,883
16,232
18,580
20,929
3 Star Gas Water heater
Gas used
MJ/year
14,010
16,756
19,503
22,249
24,996
27,742
30,489
33,235
4 Star Gas Water heater
Gas used
MJ/year
12,170
14,871
17,572
20,273
22,974
25,675
28,375
31,076
Table 13 Gas consumed by three and four star gas storage water heaters vs occupancy
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 29 of 99
2.17.1 Gas Consumed By a Solar Hot Water System
AS/NZS 4234 gives a method to evaluate the savings from a solar water heater. This method
has been used to estimate the savings for solar water heaters to be eligible for rebates in
Victoria up until early 2013. The data for all water heaters listed has been analysed and those
models that have been installed in the last two years of the rebate program have been used to
calculate the likely savings over a range of hot water loads, relating to occupant numbers.
The average solar water heater savings in Zone 4 (Southern Victoria) was 75% for the
AS/NZS4234 ‘small’ load, approximately 120 litres/day, and 68% for the AS/NZS4234
‘medium’ load, approximately 200 litres/day.
Some solar water heaters had performance estimates for both small and medium loads. These
were used to estimate the reduction in solar contribution of solar water heaters (% saving) as
more hot water was withdrawn. Whilst the percentage saved decreased, the actual energy
saved increased as the load also increased more, i.e. at higher load the energy saved is a
smaller percentage of a larger figure. Using the two loads available, a relationship was
estimated between the number of occupants and the energy saved. Figure 4 shows the results
of this calculation.
Figure 4 Gas used by water heaters and saved by solar vs number of occupants
2.17.2 Performance in Northern Victorian compared to Southern Victoria
The Northern part of Victoria has a better solar climate than the Southern part of Victoria. It
is generally considered that the Great Dividing Range is the boundary between the
performance zones. This corresponds with the AS/NZS4234 division between Zone 3 (Nth
Victoria and NSW) and Zone 4 (Southern Victoria and Tasmania) which corresponds
approximately to the Great Dividing Range.
0
5
10
15
20
25
30
35
1 2 3 4 5 6 7 8
M J / Year ( '000s)
Occupants
Gas used v's Occupancy
4 Star Gas Heater
Gas saved SWH
Gas Used SWH
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 30 of 99
The improved performance due to the clearer skies inland has been estimated by comparing
the number of Small Technology Certificates (STCs) created for the same product for Zone 4
and Zone 3 from the Clean Energy Regulator (CER) listing. It was established that the
increase in performance is approximately 13%. Consequently savings attributable to a solar
water heater were increased by 13% for the Northern region of Victoria and the Mildura area.
2.17.3 6-Star Gas Instantaneous Water Heater Consumption
The performance of a six star instantaneous gas water heater has been estimated based on the
performance of water heater with the following parameters.
Electric Fan power
70
W
Fan run on after water stops flowing
30%
Standby
5
W
HW Flow rate
6
l/min
Table 14 Performance parameters for a six star water heater
Note that electricity is consumed in a high efficiency gas instantaneous water heater;
To operate the control system, a constant consumption, and
To operate the forced combustion fan when the water is being heated, a variable
consumption.
Using the parameters above the consumption of a 6 star instantaneous gas water heater and
the savings compared to a 4 star storage gas water heater are show in the result Section 3.5.
2.17.4 Cost of Solar Water Heaters
The data from the SV SHW rebate program was analysed to calculate the cost of supply and
installation of solar water heaters over the final 2 years of the program. There were 1716
individual installations over this period. The supply cost, rebate and support from VEET and
RET were listed separately. As the installation during renovation will generally qualify for
VEECs and STCs the savings to the householder from these were included. The average
price was $3577 and the average installation cost was $1687, a total of $5264.
The cost of supply of all models that had more than 5 installations was analysed. There were
1040 installations where the model was installed 5 or more times in the two year period. The
relationship between solar savings and supply costs were analysed as shown in Figure 5
below. There is no significant relationship between the solar savings and the supply cost of
the appliance.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 31 of 99
Figure 5 Relationship between solar savings and supply costs
Consequently, it is reasonable to use an average price and average savings in the model
developed for this project.
2.17.5 Cost of Gas Water Heaters
The cost of supply and installation of gas water heaters has been estimated from prices
available from a variety of sources
t
.
The supply and installation costs for a four star storage water heater supply and install costs
vary between $1940 and $2140. Therefore the total cost used for the base case is the average
$2040). It is assumed that the existing gas supply pipe will be sufficient to supply the new
water heater.
The cost to supply and install a six star instantaneous gas water heater often requires
upgrading the gas supply as the existing gas pipe is insufficient to provide the amount of gas
needed to these appliances. Therefore, the total cost of the high efficiency gas option is
estimated at $2735.
2.17.6 Operating Life of Water Heaters
The best information on life of water heaters is given in the BIS Schrapnel reports on
appliances replaced. The results from the 2008, 2010, and 2012 surveys are given in their
report of 2012 (see Table 15 below). It indicates that solar water heaters last 28% longer than
gas storage water heaters. Gas instantaneous water heaters last 2% longer than gas storage
water heaters.
This difference in life is accounted for in the levelised cost of energy calculation by adding
that percentage to the cost of the gas storage water heater which accounts for the cost from the
next system purchased whilst the longer life system is still operating.
0%
20%
40%
60%
80%
100%
$- $1,000 $2,000 $3,000 $4,000 $5,000 $6,000
Pertcentage Savings
Supply Cost
Solar savings (med. load) vs supply cost of solar
water heaters
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 32 of 99
Year Reported
Total
Electric Storage
Gas Storage
Gas Instant
Solar
2012
12.6
12.7
12.0
12.6
14.8
2010
12.8
12.8
12.2
12.3
17.7
2008
12.9
13.2
12.4
12.4
14.4
Average
12.8
12.9
12.2
12.4
15.6
Table 15 The age of replaced water heaters
u
2.17.7 Calculation of Annualised Cost
Annualised cost is a method to compare products that have different capital cost, running
costs and lifetimes. It has been used by GWA (2010)
v
.
The annualised cost is the total present value of the costs of a water heater divided by the
expected life of the water heater. It equalizes the differences in service lifetimes of different
technologies using an Internal Rate of Return (equivalent to a discount rate). The annualised
energy charges are the average projected energy cost over the service life of the water heater,
calculated by multiplying the projected energy tariff (c/MJ) by the energy consumed (MJ/yr)
by a water heater of that type to deliver the estimated hot water load requirement for the
household.
2.17.8 Discount Rate
The discount rate used is calculated from the energy escalation rate, the inflation rate and the
mortgage rate used to finance the new water heater, assuming that a mortgage redraw is used
to fund the complete renovation cost. The discount rate calculate as
  



Equation 1
The figures used in the spreadsheet are given in Table 16 below
Energy escalation
6.0%
Inflation rate
1.0%
Mortgage rate
6.0%
Consequent Discount Rate
1.0%
Table 16 Rates used to calculate the discount rate
2.17.9 Cost of Energy Saved
All of the evaluations of comparative savings from different water heaters presented above
require the fuel cost to be estimated over the life of the water heater. An alternative method to
evaluate if a more efficient water heater is a worthwhile investment is to estimate the energy
saved over the lifetime of the system and divide that by the difference between the purchase
and installation costs of the comparative systems adjusted for the difference in life.

  



  


 
Equation 2
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 33 of 99
2.18 Performance of Solar Photovoltaic Systems
2.18.1 Electricity Consumption
Electricity consumption will be impacted by the energy efficiency measures implemented
within the renovation. However in order to have an indication of the range of electricity
consumption the government website EnergyMadeEasy
w
was consulted. That website gives
daily and total electricity consumption by season for a range of occupants. This is shown in
Table 43 in Appendix Section 7.7. The relationship between occupancy and electricity use is
shown in Figure 6. It follows the linear equation below:
   
Equation 3
Figure 6 Electricity consumption vs occupancy for Victoria
2.18.2 System Size
According to Sunwiz, the overall average size for PV systems installed in Victoria is 2.4 kW
x
.
This is similar to the average across all Australia. However, as feed in tariffs have reduced to
generally less than 1/3 of the retail cost of electricity, the financial optimum sizing has
reduced. Moyse
y
states that ‘export percentage (the portion of energy sent out to the grid) is
now one of the major determinant of payback times’ and ‘when it comes to getting the best
return on your investment in PV, smaller seems to be increasingly better. Gill
z
indicates that
for household use of 12kWh/day the financially optimum array size is approx. 1 kW and for
20kWh/day it is 1.6 kW
aa
.
Consequently, this analysis will consider an array size of approximately 1.5 kW. Compared to
a 2.4 kW system a larger proportion of the locally generated electricity will be used within the
house. Note that displaced purchase of electricity is more valuable (at a price of 27.5 to 30
cents/kWh) than electricity exported from which the householder will receive income of 8
cents/kWh.
0
2000
4000
6000
8000
10000
12000
0 1 2 3 4 5 6 7 8
Annual Electricity Consumption
kWh/yr
Household occupancy
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 34 of 99
It is noted that the 1.5 kW system never outputs 1.5 kW from the inverter. Due to the inverter
not being 100% efficient, the rated panel output would never be the amount available after the
inverter. As there are a whole number of panels to be installed it is often the case that a
nominal 1.5 kW system will have a slightly higher capacity and could put out 1.5 kW after the
inverter in that case.
2.18.3 Performance Calculation
The NREL SAM
bb
calculation methodology was used to evaluate the solar electricity
available from a 1.5 kW system. SAM has weather data available for Melbourne,
Tullamarine, Ballarat and Mildura.
The modelling included a tilt of 25 degrees from horizontal and was undertaken with the
panels facing North, North East and North West.
The electrical load from the household is required to estimate the percentage exported. The
profile in Figure 37 was scaled to give the seasonal loads representative of Victorian
households as shown Table 43
cc
in Appendix 7.7.
2.18.4 Electricity Used On Site and Exported
As the cost of purchasing electricity from the grid is higher than the price paid for electricity
exported from the site to the grid, the greater amount used on site the better the financial
return from the system. Consequently there is a reduced financial benefit from the PV system
as the dwelling becomes more efficient. As this is a complex interaction and will depend on
the electricity consumed by other appliances and particularly the daily electricity consumption
profile, a constant profile has been used and scaled to meet the seasonal loads. Note that the
savings made by implementing energy efficiency measures in the household are not
accounted for in the spreadsheet calculations.
Figure 7 and Figure 8 illustrate this for Tullamarine.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 35 of 99
Figure 7 PV generated electricity consumed on site (saved) and exported
Figure 8 The impact on electricity bills from PV generation
2.18.5 Cost of PV System
The costs of PV systems have reduced significantly over the recent past due firstly to high
volumes of sales following attractive feed in tariffs and recently due to increased production
and lowering of sales growth leading to a more competitive market.
In order to have a realistic price, a provider of quality systems was approached in November
2013. They suggested the appropriate range for a 1.5 kW system ‘should be $3000-$4000’ but
said that ‘There will always be someone out there doing it for less’. They also suggested that
a realistic cost for a tilt frame was $500.
-
500
1,000
1,500
2,000
2,500
0 2000 4000 6000 8000 10000 12000
PV generated kWh/yr
Household Load kWh/yr
Tullamarine
exported Saved Total
$-
$100
$200
$300
$400
$500
$600
0 2000 4000 6000 8000 10000 12000
PV impact on bills
$ / yr
Household Load kWh/yr
Tullamarine
$ saved $ earned $ total
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 36 of 99
From current advertising offers it seems that prices in the order of $2500 - $3000 are
available. Consequently, the model used a capital cost (purchase and installation) of $3000
with an additional cost of $500 should the roof be flat or if there is insufficient space for both
a solar water heater (~5m
2
) and a PV system (~10 m
2
) on the north facing roof.
2.18.6 Cost of Energy Saved
The cost of energy saved is calculated in the same manner as for the solar water heating
system. That is the total upfront cost divided by the total energy generated by the PV system.
The total energy generated was assumed to be over a twenty year lifetime. Note that many
systems have a longer lifetime, however, twenty years was chosen as generation often reduces
over the lifetime of the system.
2.18.7 Annualised Costs/Benefits
The annualised costs of ownership are calculated in a similar manner to the solar hot water
calculation. However, the PV system results in savings compared to sourcing electricity from
the grid so the annual expenditure is negative
dd
. Consequently as the savings from the PV in
these cases is less than the annualised cost of purchase and installation the annualised figure is
a benefit not a cost. If the cost of PV increased or the cost of grid power decreased or the
percentage exported at a low feed in tariff increased, then this could be a negative figure.
2.18.8 PV Output and Cooling Peak Load
The PV hourly output is compared with the hourly cooling peak load from the peak load
analysis results. To demonstrate the worse-case scenario, the Estate style typology is chosen
for this comparison. Due to the heavy-weight construction of this typology the peak load
would be later in the day when the PV output is far from its maximum.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 37 of 99
3 Results
3.1 Baseline
Below are the estimated energy demands from the NatHERS simulation results of the four
typologies in CZ6 (Tullamarine). Figure 9 shows the results with usage profile “Away during
the day” with central heating/cooling and Figure 10 is results of “Always home” with central
heating/cooling as well.
Figure 9 Annual Energy Demand for the Baselines in CZ6, with “Away during the day” usage profile
Figure 10 Annual Energy Demand for the Baselines in CZ6, with “Always home” usage profile
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 38 of 99
3.2 All Measures Best Practice
Similarly, the all measures best practice energy demand results from NatHERS simulations
for CZ6 are presented in Figure 11 and Figure 12.
Figure 11 Annual Energy Demand for the All Measures Best Practices in CZ6, with “Away during day” usage profile
Figure 12 Annual Energy Demand for the All Measures Best Practices in CZ6, with “Always home” usage profile
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 39 of 99
3.3 Lighting
Climate: Ballarat
(66)
Typology: Heavyweight Inter-War
Area (m²): 135.8
Baseline Ceiling
Insulation R3.5
Heating
(MJ/m²/yr)
Sensible
Cooling
(MJ/m²/yr)
Latent
Cooling
(MJ/m²/yr)
Total
Energy
(MJ/m²/yr)
%
Difference
Decimal
Stars
Uninterrupted R3.5
but with 3 vented
downlights added
441.12
16.85
1.99
459.96
0.94%
3.25
Uninterrupted R3.5
(equivalent to no
downlights)
437.08
16.63
1.96
455.67
-
3.28
R3.5 on all but 0.09
m² having no
insulation
437.48
16.74
1.96
456.18
0.11%
3.28
As above but with 3
vented downlights
added
441.48
16.86
1.96
460.30
1.02%
3.25
Table 17 Ceiling insulation with downlight clearances test results
In rating mode the NatHERS simulation engine does not calculate the lighting energy
consumption. However the infiltration caused by using vented downlights is included as part
of the air-flow calculation which affects the heating/cooling energy demands. A low energy
lighting plan for the house (vented downlights used only in areas where needed i.e. kitchen
bench, for the Baseline) was proposed as one of the energy efficiency measures. According to
the NatHERS Technical Note 2
ee
, clearances are required around the downlights. The results
of the simulations performed, which explore the significance of the heat loss and gain through
the uninsulated ceiling, are listed in Table 17.
From the simulation results shown in Table 17, the loss of ceiling insulation due to the use of
downlights only affect the heating/cooling energy demands by about 1%. The “Low energy
lighting plan for house” is excluded from this study.
For details of the Baseline lighting upgrade please refer to Appendix Section 7.2 and 7.3.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 40 of 99
3.4 Heating Systems
Table 18 is the cost benefit analysis of upgrading the heating systems from 3 Stars to 5 Stars
(with the upgraded duct from NCC compliant R1.0 to R1.5) for the Baseline scenario with the
always home usage profile in CZ6. Note that the building shell remains unchanged.
Typology
Average differential cost to
purchase and install ($)
5 Stars heating systems
Cost savings
per annum ($)
Payback
period
Weatherboard cottage
882
389
2.3
Inter-war house
950
313
3.0
Double fronted brick veneer
1003
375
2.7
Estate style
834
239
3.5
Table 18 Cost of 5 Stars heating & cooling systems for the Baseline scenario in CZ6
The same analysis for the All Measures Best Practice scenario in the same CZ6 is shown in
Table 19.
Typology
Average differential cost to
purchase and install ($)
5 Stars heating systems
Cost savings
per annum ($)
Payback
period
Weatherboard cottage
915
77
12
Inter-war house
975
77
13
Double fronted brick veneer
1035
72
14
Estate style
855
78
11
Table 19 Cost of 5 Stars heating & cooling systems for All EEM Applied scenario in CZ6
For the full set of data please refer to the Excel workbook “ExcelSpreadsheetDevelopment -
2014-06-30(Variation)-v19.xlsm
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 41 of 99
3.5 Hot Water Systems
See Appendix 7.6 for a complete analysis
Occupants
1
2
3
4
5
6
7
8
Hot water
consumption
litres/day
65
99
133
167
201
235
269
303
MJ/day
12.29
18.72
25.15
31.58
38.01
44.44
50.87
57.3
MJ/Yr
4489
6837
9186
11535
13883
16232
18580
20929
4 Star Gas Water heater
Gas used
MJ/year
12170
14871
17572
20273
22974
25675
28375
31076
$/yr cost
Metro
229
280
319
355
402
427
472
517
Regional-North
226
276
319
361
409
443
489
536
Regional-South
226
276
319
361
409
443
489
536
Mildura
392
479
566
653
740
827
914
1001
Annualised cost
$/yr
Metro
382
430
466
500
544
568
610
652
Regional-North
379
425
466
505
550
582
626
669
Regional-South
379
425
466
505
550
582
626
669
Mildura
534
616
697
779
860
942
1023
1105
Solar water heater
Savings% South
Compared to 4
star gas water
heater
83%
79%
74%
70%
65%
61%
57%
53%
Saving % North
96%
90%
85%
80%
75%
70%
65%
61%
Gas saved South
MJ/yr
10080
11687
12989
14154
14975
15687
16180
16453
Gas Saved North
MJ/yr
11629
13452
14928
16251
17185
17996
18558
18872
$/yr Saved
Metro
190
220
227
248
262
261
269
274
Regional-North
219
253
261
284
301
300
309
314
Regional-South
187
217
231
252
267
271
279
284
Mildura
374
434
481
524
554
580
598
609
Annualised cost
$/yr
Metro
374
393
422
436
466
491
525
562
Regional-North
344
358
391
408
437
469
504
542
Regional-South
373
392
419
438
469
496
531
570
Mildura
353
379
415
456
509
565
628
699
6 star gas
Gas consumed
MJ/yr
8571
11060
13549
16038
18526
21015
23504
25993
Gas saved
MJ/yr
3599
3811
4023
4235
4447
4659
4871
5083
Elect. consumed
kWh/yr
49
52
55
58
61
64
67
70
$/yr Saved
Metro
54
57
55
58
61
60
63
65
Regional-North
52
55
55
58
61
61
64
67
Regional-South
52
55
55
58
61
61
64
67
Mildura
101
107
113
119
125
131
137
143
Annualised cost
$/yr
Metro
384
429
468
498
540
564
604
644
Regional-North
383
427
468
504
546
578
619
660
Regional-South
383
427
468
504
546
578
619
660
Mildura
493
569
644
720
796
872
948
1024
Table 20 Performance of gas boosted solar and six star gas compared to a four star storage gas water heater
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 42 of 99
3.5.1 Annualised costs
Annualised costs are plotted below. The figures indicate that a solar water heater has the
lowest annualise cost, and that the two gas options are effectively the same cost on an
annualised basis, except in Mildura where the six star water heater is always the more
economical option of the gas water heaters, due to higher gas prices.
Figure 13 Annualised cost of using each of the three options - Metro Area
Figure 14 Annualised cost of using each of the three options Regional- North Area
300
350
400
450
500
550
600
650
700
1 2 3 4 5 6 7 8
Metro Annualised Cost
4 star gas water heater Solar water heater 6 star gas
Occupants
300
350
400
450
500
550
600
650
700
1 2 3 4 5 6 7 8
Regional-North Annualised Cost
4 star gas water heater Solar water heater 6 star gas
Occupants
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 43 of 99
Figure 15 Annualised cost of using each of the three options - Regional - South Area
Figure 16 Annualised cost of using each of the three options - Mildura Area
Cost of energy saved $/MJ
Comparison of water heating with the four star gas storage water heater
Occupants
1
2
3
4
5
6
7
8
Solar with
Gas
Boosting
Regional-South
0.015
0.013
0.012
0.011
0.010
0.010
0.009
0.009
Regional-North
0.013
0.012
0.010
0.009
0.009
0.008
0.008
0.008
Metro
0.015
0.013
0.012
0.011
0.010
0.010
0.009
0.009
Mildura
0.013
0.012
0.010
0.009
0.009
0.008
0.008
0.008
6 Star Instantaneous Gas
0.007
0.007
0.007
0.007
0.006
0.006
0.006
0.006
Table 21 Cost of energy saved $/MJ compared to four star gas storage water heater
300
350
400
450
500
550
600
650
700
1 2 3 4 5 6 7 8
Regional-South Annualised Cost
4 star gas water heater Solar water heater 6 star gas
Occupants
300
400
500
600
700
800
900
1000
1100
1200
1 2 3 4 5 6 7 8
Mildura Annualised Cost
4 star gas water heater Solar water heater 6 star gas
Occupants
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 44 of 99
3.5.2 Summary
Gas boosted Solar water heaters are always more cost effective than a four star
gas water heater.
High efficiency six star gas water heaters are as cost effective or better than four
star gas water heaters, especially so in households with higher hot water use and
in regions where gas prices are higher.
An average gas boosted solar water heater will save 53% in large (8 occupant)
households to 83% in Small (single occupant) households gas compared to a four
star gas water heater in Southern Victoria. It will save more in Northern Victoria.
Based on Annualised costs;
Gas boosted Solar water heaters are always the most cost effective option
For all of Victoria;
The money a householder needs to invest to save a MJ of gas is equivalent to, or
less than, the current cost of gas for both a gas boosted solar water heater and a
six star instantaneous gas water heater when compared to a four star water heater.
These options are always less expensive in homes where there are three or more
occupants.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 45 of 99
3.6 Solar PV Systems
See Appendix 7.7 for a complete analysis
Occupants
1
2
3
4
5
6
7
8
Load
3886
4808
5691
6613
7526
8440
9355
10253
Tullamarine
2,169 kWh/year
exported
1,030
859
711
572
446
339
247
172
imported
-2,747
-3,499
-4,234
-5,017
-5,803
-6,611
-7,433
-8,256
Saved
1,139
1,309
1,457
1,597
1,723
1,829
1,921
1,997
Export %
47%
40%
33%
26%
21%
16%
11%
8%
self-use %
53%
60%
67%
74%
79%
84%
89%
92%
$ saved
$313
$359.91
$400.49
$438.84
$473.52
$502.76
$528.04
$548.89
$ earned
$82.41
$68.73
$56.92
$45.76
$35.66
$27.15
$19.79
$13.72
$ total
$395.33
$428.64
$457.41
$484.60
$509.18
$529.91
$547.83
$562.61
Ballarat
2,188 kWh/year
exported
1003
826
676
537
411
307
216
143
imported
-2701
-3445
-4179
-4962
-5749
-6559
-7383
-8209
Saved
1,185
1,363
1,512
1,652
1,777
1,881
1,972
2,045
Export %
46%
38%
31%
25%
19%
14%
10%
7%
self-use %
54%
62%
69%
75%
81%
86%
90%
93%
$ saved
$355.07
$408.22
$452.95
$494.85
$532.37
$563.65
$590.75
$612.64
$ earned
$80.25
$66.05
$54.11
$42.92
$32.90
$24.55
$17.31
$11.47
$ total
$435.32
$474.28
$507.06
$537.77
$565.28
$588.20
$608.07
$624.11
Melbourne
1,982 kWh/year
exported
920
765
633
509
397
303
221
154
imported
-2824
-3592
-4343
-5141
-5941
-6761
-7594
-8425
Saved
1,062
1,217
1,348
1,473
1,585
1,679
1,761
1,828
Export %
46%
39%
32%
26%
20%
15%
11%
8%
self-use %
54%
61%
68%
74%
80%
85%
89%
92%
$ saved
$291.76
$334.35
$370.53
$404.80
$435.58
$461.41
$483.90
$502.40
$ earned
$73.59
$61.20
$50.67
$40.69
$31.73
$24.22
$17.67
$12.28
$ total
$365.36
$395.55
$421.20
$445.49
$467.31
$485.62
$501.57
$514.69
Mildura
2,521 kWh/year
exported
1296
1098
920
749
591
451
331
231
imported
-2661
-3385
-4091
-4842
-5595
-6370
-7165
-7964
Saved
1,224
1,423
1,600
1,772
1,930
2,070
2,190
2,290
Export %
51%
44%
37%
30%
23%
18%
13%
9%
self-use %
49%
56%
63%
70%
77%
82%
87%
91%
$ saved
$367
$426
$479
$531
$578
$620
$656
$686
$ earned
$104
$88
$74
$60
$47
$36
$26
$18
$ total
$471
$514
$553
$591
$626
$656
$683
$705
Regional South
2169 kWh/year
exported
1030
859
711
572
446
339
247
172
imported
-2747
-3499
-4234
-5017
-5803
-6611
-7433
-8256
Saved
1139
1309
1457
1597
1723
1829
1921
1997
Export %
47%
40%
33%
26%
21%
16%
11%
8%
self use %
53%
60%
67%
74%
79%
84%
89%
92%
$ saved
$341.11
$392.32
$436.56
$478.37
$516.18
$548.04
$575.60
$598.33
$ earned
$82.41
$68.73
$56.92
$45.76
$35.66
$27.15
$19.79
$13.72
$ total
$423.51
$461.05
$493.48
$524.12
$551.84
$575.19
$595.39
$612.05
Table 22 Summary of the PV system analysis results
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 46 of 99
3.6.1 PV Generation across Victoria
Figure 17 PV generation by location
It can be seen that the generation in Tullamarine is midway between Melbourne (3.7% lower)
and Ballarat (3.8% higher). The generation in Mildura is 19.8% higher than Tullamarine
3.6.2 Cost of Energy Produced
The cost of energy produced is calculated in the same manner as for the cost of energy saved
for solar water heating system. That is the total upfront cost divided by the total energy
generated by the PV system. The total energy generated was assumed to be over a twenty
year lifetime. Note that many systems have a longer lifetime, however, twenty years was
chosen as generation often reduces over the lifetime of the system. The results are given in
Table 23Table 45.
Region
Installed on Nth facing
sloping roof
Installed on flat roof or where a
rack is required to face North
Southern Victoria
$ 0.077
$ 0.090
Northern Victoria
$ 0.060
$ 0.070
Table 23 Cost of electricity produced
3.6.3 Annualised Costs/Benefits
The annualised costs of ownership are calculated in a similar manner to the solar hot water
calculation. However, a 1.5 kW PV system results in savings compared to sourcing electricity
from the grid so the annual expenditure is negative
ff
. Consequently as the savings from the PV
in these cases is less than the annualised cost of purchase and installation the annualised
figure is a benefit not a cost. If the cost of PV increased or the cost of grid power decreased
or the percentage exported at a low feed in tariff increased, then this could be a negative
figure.
Annualised Savings are given in Table 24:
Tullamarine Ballarat Melbourne Mildura
Generation
2,169 2,188 1,982 2,521
-
500
1,000
1,500
2,000
2,500
3,000
Generation kWh/year
PV Generation
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 47 of 99
Occupants
1
2
3
4
5
6
7
8
Load
3886
4808
5691
6613
7526
8440
9355
10253
Annualised
$/year
Tullamarine
$207
$237
$263
$287
$ 309
$328
$344
$358
Ballarat
$ 243
$278
$308
$335
$360
$381
$399
$413
Mildura
$ 275
$314
$349
$383
$414
$442
$466
$ 486
Melbourne
$ 180
$207
$230
$252
$272
$288
$303
$314
Table 24 Annualised savings by location and Household size/load
3.6.4 PV Output and Cooling Peak Load
Figure 18 PV Output and Cooling Peak Load of Estate style typology in CZ6
The comparison of PV output and the hourly cooling peak load is shown in Figure 18. The
total internal heat gain is the sum of the sensible and latent heat gain of the “always home”
occupancy pattern. The hour on the x-axis is standard time hour. Figure 19 shows the net
export (+ve) and import (-ve).
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 48 of 99
Figure 19 Net export (+ve) and import (-ve)
3.6.5 Summary
With current electricity tariffs and feed in tariffs the most cost
effective option is to size a PV system so that most of the electricity it
produces is used onsite.
A 1.5 kW system will save the household $200 to $480 annually over
its operating life including paying for the purchase and installation
price.
A PV system installed in Northern Victoria can produce up to 20%
more than in Southern Victoria
If there is no suitable North facing roof available, a North Easterly
orientation will provide more Electricity than a North Westerly
orientation. However, within 45 degrees of true north there is less
than 10% decrease in output.
If a flat roof or an unsuitable orientation is the only option, then racks
to tilt and orientate the PV modules can be used. This will add
approximately 15% to 20% to the installed cost.
The money a householder needs to invest to save a kWh of electricity
is significantly less than the current cost of electricity. 6 -9 c/kWh
compared to 27 - 30 c/kWh to purchase
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 49 of 99
3.7 Building Fabric Improvements
The additional cost of renovating the house’s building envelope (both existing and extension)
from Baseline to Best Practice with one of the energy efficiency measures applied are listed in
Table 25:
Energy Efficiency Measure
Additional cost ($)
Weatherboard
cottage
Inter-war
house
Double
fronted
brick veneer
Estate
style
Ceiling
3,074
2,194
2,441
2,065
Roof
814
974
699
1,074
External Wall
2,212
3,986
1,948
1,902
Subfloor
2,448
1,641
1,945
990
Low-E Clear Glazing
7,049
7,574
9,485
5,754
Double glaze clear with 12mm Air
7,509
8,001
9,687
5,862
Double glaze Low-E 12mm argon
in Improved Aluminium Frame to
extension windows
8,939
9,326
10,313
6,195
Double glaze Low-E 12mm argon
in Improved Aluminium Frame to
all windows
16,567
17,398
19,812
11,931
Draught Proofing*
1,551
2,096
2,201
1,648
Lighting Type
1,054
1,289
1,054
820
All Measures Best Practice**
27,720
29,578
30,101
20,430
*We assume all the new aluminium frame windows in the extension have weather strip around sashes. Only existing
windows needed to be weather sealed.
For a full list of draught proofing measures, please refer to Appendix Section 7.2 or 7.3, energy efficiency measures item 9
“Air sealing”
gg
* *Equipped with all 7 improvements and the highest performing of the fenestration improvements Generic DG Low-e
argon in improved Aluminium frame to both existing and extension windows
Table 25 Building Fabric improvement: additional cost to upgrade from Baseline to selected EEM
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 50 of 99
Table 26 is the building fabric cost analysis for the All Measures Best Practice scenario in
CZ6.
Typology
Cost for the
renovation ($)
Cost savings per
annum ($)
Payback
period
Weatherboard cottage
32,000
Max
1370
23
Min
1180
27
Inter-war house
34,600
Max
987
35
Min
956
36
Double fronted brick veneer
38,400
Max
1280
30
Min
1220
31
Estate style
25,500
Max
681
38
Min
650
39
Table 26 Building fabric cost analysis for the All Measures Best Practice scenario in CZ6
For the full set of data please refer to the Excel workbook “ExcelSpreadsheetDevelopment -
2014-06-30(Variation)-v19.xlsm”.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 51 of 99
3.8 Peak Load Analysis
Figure 20 to Figure 23 are the steady state peaks and metered energy of the peak load analysis
for NCC CZ6. For the full set of graphs and data please refer to the excel workbook “Peak
Load Analysis - Graphs and Data - 2014-06-30.xlsx”.
Figure 20 Steady state peak of gas heating (MJ/h) for CZ6
Figure 21 Steady state peak of electrical cooling (kW) for CZ6
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 52 of 99
Figure 22 Total annual metered energy of heating (MJ/yr) for CZ6
Figure 23 Total metered energy of cooling (kW/yr) for CZ6
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 53 of 99
3.9 Comfort Analysis
The house living areas (exclude wet areas) are divided into two types: daytime and night-time
zone according to the NatHERS Technical Note 1
hh
.
The daytime and night-time zone heating /cooling degree.hours for a comfort range (18°C
23°C) are calculated and example graphs are shown below. For the full set of graphs and data
please refer to the excel workbook “Health and Comfort Data Analysis - Graphs and Data -
2014-06-18.xlsx”.
Figure 24 Daytime zone cooling degree.hour to Base 23°C in CZ6
Figure 25 Night-time Zone heating degree.hour to Base 18°C in CZ6
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 54 of 99
The max/min temperatures of daytime/night-time zone, together with the outdoor max/min
temperatures of the corresponding climate zone are shown in the example graphs below. For
the full set of graphs and data, which includes the time and date when the max/min
temperatures occur, please refer to the same excel workbook “Health and Comfort Data
Analysis - Graphs and Data - 2014-06-18.xlsx”.
Figure 26 Daytime zone max temperature difference between Baseline and All Measures Best Practice in CZ6
Figure 27 Night-time zone min temperature difference between Baseline and All Measures Best Practice in CZ6
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 55 of 99
3.10 Health Analysis
Similar to the Comfort Analysis but with a different tolerable range (13°C 30°C), the
daytime and night-time zone heating /cooling degree.hours are calculated and example graphs
are shown below. Full set of graphs and data are in the same excel workbook “Health and
Comfort Data Analysis - Graphs and Data - 2014-06-18.xlsx”.
Figure 28 Daytime zone cooling degree.hour to Base 30°C in CZ6
Figure 29 Night-time zone heating degree.hour to Base 13°C in CZ6
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 56 of 99
4 Interpretation
4.1 General
In general, all of the energy efficiency measures simulated for this project can improve the
comfort of the occupants and reduce the extreme temperatures inside the house. Peak loads of
heating and cooling equipment can also be reduced. House owners can select a smaller
heating/cooling system to save money or use a similar amount to buy a higher efficiency
system.
When the house is not heated or cooled, the internal temperature can be uncomfortably
high/low and the dwellings will be unsuitable for occupants to stay. The maximum and
minimum indoor temperatures for daytime and night-time zones, with Baseline and Best
Practice energy efficiency measures applied are set out in Table 27 and Table 28. These
results cover all typologies in this study. Generally, with better energy efficient measurements
applied the internal temperatures can be maintained nearer to the tolerable range.
Daytime Zones
Min. (°C)
Max. (°C)
Climate Zone
NCC 4
NCC 6
NCC 7
NCC 4
NCC 6
NCC 7
Outdoor
0.2
0.2
-3.3
42.7
38.6
37.5
Baseline
6.27
4.70
2.93
42.48
40.68
37.08
Best Practice
10.35
8.13
6.63
41.65
38.83
35.72
Table 27 Construction Influence on Maximum and Minimum Temperatures in Daytime Zone,
Night-time Zone
Min. (°C)
Max. (°C)
Climate Zone
NCC 4
NCC 6
NCC 7
NCC 4
NCC 6
NCC 7
Outdoor
0.2
0.2
-3.3
42.7
38.6
37.5
Baseline
5.63
4.75
2.55
44.15
40.70
37.13
Best Practice
10.33
8.75
7.30
40.83
39.38
36.07
Table 28 Construction Influence on Maximum and Minimum Temperatures in Night-time Zone
In the NatHERS simulation, when outside air is beneficial for cooling, the window and door
openings are assumed to be open and the house is cooled by cross and stack ventilation. All
the annual total cooling degree hours of the house models should have values lower than the
outdoor degree hour (+ve values in the graphs presented).
From the comfort and health data analysis results, the cooling degree hours and maximum
indoor temperature are counterintuitive. There are simulations with cooling degree hours and
maximum indoor temperature higher than the outdoor degree hour / temperature, which
implies the window opening function in AccuRate does not work. When the outside air is
beneficial for cooling, the openings are still close.
Another analysis carried out is the peak load analysis. The all measures best practice scenarios
have a reduction in peak loads and thus in heating/cooling energy consumptions as shown in
Table 29 which covers all typologies used in this study.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 57 of 99
Climate Zone
% reduction when selected Baseline equipped with all energy
efficiency measures*
Steady State
Peak
Gas Heating
(MJ)
Steady State
Peak
Electrical
Cooling
(kW)
Total Metered
Energy -
Heating
(kWh)
Total Metered
Energy -
Cooling
(kWh)
NCC 4
Max
-88%
-77%
-88%
-76%
Min
-82%
-57%
-81%
-56%
NCC 6
Max
-87%
-78%
-87%
-78%
Min
-75%
-58%
-74%
-57%
NCC 7
Max
-85%
-95%
-85%
-95%
Min
-74%
-61%
-74%
-60%
Table 29 Peak load analysis summary
* Equipped with all 7 improvements and the highest performing of the fenestration improvements Generic DG Low-e argon
in improved Aluminium frame to both existing and extension windows
On a clear and sunny day, the 1.5 kW PV system used in this analysis has a higher net export
for the All Measures Best Practice scenarios than the Baseline, either with lower or higher
efficiency heating/cooling appliances. For the Baseline scenario, the PV system has a net
export only until about 12 noon.
The cost benefit of upgrading the heating systems, from 3 stars to 5 stars, is also analysed. In
general, higher star rating heating appliances are more expensive (higher in capital cost) but
more efficient systems reduce the energy consumption (operating cost).
The payback period of upgrading from 3 Star to 5 Star heating system for the Baseline
scenario is less than 4 years. However, as shown in Section 3.4, the payback period of the
same analysis for the All Measures Best Practice scenario, is over 10 years which is usually
unattractive to house owner.
4.2 Spreadsheets in a Workbook
The “ExcelSpreadsheetDevelopment - 2014-06-30(Variation)-v19.xlsm” is developed for
sorting the simulation results as desired.
On the “Main” worksheet, the desired simulation results can be selected from the 5 drop-
down lists. The price of the gas and electricity can be input on the same worksheet for the cost
calculations. By pressing the button the excel workbook can sort, create and display the
results in the following 2 worksheets:
“RenovationsChecklist” is developed to have the same output format for the SV to
develop their online tools. It shows the building fabric cost and payback period of the
selected scenario, and also the cost and payback period to upgrade the heating systems
to 5 Stars.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 58 of 99
“SortedResults” contains detailed results, such as energy demands and consumptions,
cost break-down of applying selected energy efficiency measures and saving per
annum.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 59 of 99
5 Conclusions and Recommendations
This report and the work that it presents demonstrates that there is much scope for cost
effective enhancement of a house renovation project from the application of Best Practice
techniques in lieu of the general practice of barely complying with the energy efficiency
provisions in the NCC (Volume Two, Section 13). Beyond the NCC provisions for the
building envelope, similar results have been found for the selection of higher performing
heating and cooling appliances relative to both the MEPS and the current slightly better than
MEPS market norm. Similarly, the installation of solar water heaters and solar PV systems
(for on-site renewable energy collection and conversion) have been shown to be viable
choices for inclusion in such renovation projects.
It is therefore recommended that these results be disseminated to the housing industry and the
home enhancement market throughout Victoria and be regularly updated to maintain currency
such as with the forecasted substantial increases in residential natural gas tariffs.
It is further recommended that other jurisdictions be fostered in applying this concept to their
own specific situations and to share any advances they might make with the initiators at
Sustainability Victoria. Such emulation can enhance this work in its completeness over time
at the lowest cost to the respective governments.
More specific recommendations are briefly discussed below.
5.1 Heat pumps and solar electric water heaters
The majority of Victorian houses have gas connections and gas is currently the preferred fuel
for water heaters, either as the only fuel or as the boost fuel for a solar water heater. However,
there are a number of Victorian houses that do not have access to natural gas, so their options
for technology to supply hot water when renovating are
electric resistance storage heating (often at lower cost off peak rates),
heat pumps (most often installed on a continuous tariff, with some impact on peak
demand),
electric boosted solar water heaters (often on an off peak tariff), or in a few cases
instantaneous electric water heaters (single rate tariff often with a high demand around
peak demand times); and
bottled gas which is more expensive than natural gas.
Due to the different tariffs and service life of the technologies it is not a simple task to
undertake this evaluation. However, adding this to the existing options could be done as a
follow up task. Knowledge of the sector and research will be required for evaluation of heat
pump performance, as;
there is a wide range of performance and price of heat pumps and
heat pumps haven’t been widely used prior to the last decade, so there is not a lot of
data on expected life.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 60 of 99
5.2 Recommended Further Work
Incorporation of RCACs
Reticulated natural gas has been assumed for the heating energy in this project but the
incorporation of RCACs in the proposed website would be a worthwhile extension of this
project. This will cover the areas beyond the reticulated gas system and accommodate the
likely reduced dominance of gas, if gas prices rise relative to electricity as is widely predicted.
The exploration of the relative energy costs and greenhouse gas emissions for reverse cycle
air-conditioners does need further assessment. ‘Off-the-shelf’ split systems can provide a
heating COP of 4.6 or higher. If this is combined with a roof top solar PV system, the energy
consumption and relative greenhouse gas emissions could be significantly reduced.
Appliance and Luminaire Efficiencies
Appliance and electric lamp efficiencies (and COPs) should be further articulated so that users
can estimate their savings whatever rated appliance they might select. This may include the
power, amp-age and wattage labelling that is attached to all appliances. In particular,
comparison with MEPS systems rather than the market norms will afford reduced payback
periods and assist home owners to be informed and resist such selection by low cost building
contractors.
Ducted System Efficiencies
In recognition of market limitations, only low and medium performance ductwork has been
considered in this project due to its current dominance in flexible ductwork manufacture.
Higher insulation value flexible ductwork is manufactured and available in Victoria and could
be included to demonstrate the cost effectiveness of making such selections at the design
stage thus deepening the market and reducing the differential costs. This has occurred in the
U.S.A. where the Department of Energy has invested in significant training and technical
support for system designers, specifiers, installers and consumers.
Targeted Fenestration
All the glazing improvement options used in this study return very high and unacceptable
payback periods with an average of about 30-300 years. One reason for this is that the
changes in glazing are applied to all windows facing all orientations and in all rooms where
this could be unnecessary for reducing energy demands. The upgrading of glazing could be
optimized by allowing for a consideration of individual room improvement subject to
orientation, function and times of occupation.
Second Storey Extensions
All four archetypes in this report are same-level extensions into the back yard. Many
householders will be contemplating upward extensions and should be afforded similar quality
advice in planning their projects.
Inclusion of Greenhouse Emissions
Comparative Greenhouse gas emissions as well as purchase price and running costs are used
by some purchasers as part of the decision making process. GHG emissions could be added to
the tool with little additional effort.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 61 of 99
Inclusion of Cooling Energy and Peak Load Savings
With rising penetration of residential air conditioning, especially in the demographic grouping
of families engaging in house renovation and extension, augurs for the inclusion of cooling
energy savings in the calculation of payback periods. This should be further enhanced by the
inclusion of reductions in peak summer demand on the social cost of electricity generation
and distribution infrastructure, especially when that cost becomes reflected in residential
tariffs using “smart” meters.
Accounting for Daylight Saving
Modification of the simulations to realistically reflect the impacts of Daylight Saving should
be implemented, especially where the cooling energy and peak loads are to be fully
considered in summer. This would require the climate data to be off-set one hour to align the
actual weather with the occupancy patterns being simulated.
Overlooked EEMs
A project like this inevitably must target EEMs of key consideration in the house renovation
market to meet project time and cost constraints. Other EEMs will emerge over time as
building technology improves and price relativities change. Those EEMs and performance
factors noted at present as being worthy of incorporation in an expanded project include:
Movable shading like awnings and fixed shading like eaves compared with minimal
eaves or parapets;
Tinted and reflective glazing in single and double glazed applications with and
without Low-E coatings;
Air-to-air heat exchange in forced ventilation for heat/cool reclaim;
Roof space solar heat capture with thermostatically controlled ventilation systems;
Roof colour and solar absorptivity;
Floor insulation to a high level, say, R 5.0 under all;
The uses of high insulation over-cladding systems, which are strongly supported in the
U.S and E.U. to significantly improve the thermal performance of existing housing;
Shading from landscaping and neighbouring homes (beneficial and detrimental);
Non-cardinal orientations, especially for the solar PV analysis where a north-westerly
aspect can reduce annual electricity output but increase the value of that output by
aligning its peak with the peak demand on the electricity grid; and
Comparison of simulated cooling energy demand peaks (with and without solar PV)
with historical electricity grid peaks using real time weather data in lieu of the climate
data applied in this project.
Longer Term Overview
Finally, this research has taken energy prices and climate data from a specific moment in
time. This can be criticised as incomplete in the context of long-term household planning.
Firstly, in recent years there have been significant changes to the prices of electricity and gas
in Australia, and there is extensive discussion about possible future leaps in energy prices.
Secondly, the effects of climate change are generally accepted and this may result in a
significant change in the degree heating and degree cooling hours for Victoria. A well
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 62 of 99
justified “climate change” climate file should be established for a theoretical 2030 and/or
2050. Many houses that are being renovated today will still be occupied in 2050. Developing
a deeper understanding of built fabric and equipment improvements for today and out to 2050
can provide homeowners with a more informed home quality improvement strategy.
Energy Partners Renovation Cost-Benefit Analysis 02 6175 5915
July 2014 Page 63 of 99
6 Acknowledgements
It would not have been possible without the kind support and help of many individuals and