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Analysis of Various Ventilation Solutions for Residential and Non-residential Buildings in Latvia and Estonia: Sustainable Buildings in Cold Climates

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Analysis of Various Ventilation Solutions for Residential and Non-residential Buildings in Latvia and Estonia: Sustainable Buildings in Cold Climates

Abstract and Figures

As the newly built and renovated buildings consume less energy for heating needs, due to better and thicker insulation, the relative energy consumption for ventilation increases. This leads to necessity for increased effectiveness of ventilation systems, but such systems are more expensive in installation therefore the most economically feasible solution must be found in each case. A specific attention should be paid to such unclassified buildings as dormitories and barracks where occupancy profile and density differs from residential buildings which are already widely analyzed. This paper presents study results of cost analysis for different ventilation strategies for case study multi-story apartment building in Latvia and Estonia. The compared ventilation strategies include natural ventilation through windows, natural ventilation by having inlet valves with natural exhaust, hybrid ventilation with inlet devices in walls and mechanical exhaust, decentralized mechanical ventilation with room based heat recovery, decentralized mechanical ventilation with apartment based heat recovery and building based centralized ventilation system. For each of these system types installation costs are estimated, based on necessary equipment and actual market prices. Afterwards annual running and maintenance costs are calculated and obtained data compared to select the optimal solution. The results show that the most cost effective system in longer time period is centralized ventilation system which serves whole staircase. Although the simpler solutions like natural or hybrid ventilation systems with air inlets through walls and mechanical exhausts are initially cheaper the energy costs to heat up the incoming air are high and therefore cost inefficient in longer time period.
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Analysis of various ventilation solutions for residential
and non-residential buildings in Latvia and Estonia
Jurgis Zemitis
1
; Anatolijs Borodinecs
1
; Targo Kalamees
2
1
Riga Technical University, Institute of Heat, Gas and Water Technology, Kipsalas street 6A,
Riga, Latvia
2
Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia
jurgis.zemitis@rtu.lv
Abstract. As the newly built and renovated buildings consume less energy for
heating needs, due to better and thicker insulation, the relative energy consump-
tion for ventilation increases. This leads to necessity for increased effectiveness
of ventilation systems, but such systems are more expensive in installation there-
fore the most economically feasible solution must be found in each case. A spe-
cific attention should be paid to such unclassified buildings as dormitories and
barracks where occupancy profile and density differs from residential buildings
which are already widely analyzed.
This paper presents study results of cost analysis for different ventilation strat-
egies for case study multi-story apartment building in Latvia and Estonia. The
compared ventilation strategies include natural ventilation through windows, nat-
ural ventilation by having inlet valves with natural exhaust, hybrid ventilation
with inlet devices in walls and mechanical exhaust, decentralized mechanical
ventilation with room based heat recovery, decentralized mechanical ventilation
with apartment based heat recovery and building based centralized ventilation
system. For each of these system types installation costs are estimated, based on
necessary equipment and actual market prices. Afterwards annual running and
maintenance costs are calculated and obtained data compared to select the opti-
mal solution.
The results show that the most cost effective system in longer time period is
centralized ventilation system which serves whole staircase. Although the sim-
pler solutions like natural or hybrid ventilation systems with air inlets through
walls and mechanical exhausts are initially cheaper the energy costs to heat up
the incoming air are high and therefore cost inefficient in longer time period.
Keywords: Ventilation, efficiency, cost analysis.
1 Introduction
One of the most important engineering systems from all is the ventilation. It has always
been present in the buildings but the exact solutions have changed during the years. The
ventilation system has evolved starting from simple natural ventilation with supply
through construction cracks or windows to fully mechanical ducted supply/exhaust ven-
tilation system with various in between solutions. This makes the choosing of the
2
optimal ventilation solution difficult in each specific situation as each type ensures dif-
ferent comfort and control level but also varies in installation and running costs. In
existing researches (1) it is stated that a VHR systems can give substantial final energy
reduction, but the primary energy benefit depends strongly on the type of heat supply
system. However for renovated buildings or some lower priced newly built buildings it
could either not be possible or feasible to install such and simpler solutions could be
chosen. This leads to necessity to carefully choose the appropriate ventilation system
type to maximize energy savings while providing good indoor air quality. Investigation
(2) have shown that in renovated apartment buildings with natural passive stack venti-
lation, the indoor air quality is quite bad and has high CO
2
concentration and relative
humidity level. Similar data on IAQ problems in multi apartment buildings shows re-
search (3) done in Estonia. Some authors (4) have already performed analysis on how
ventilation rates vary depending on chosen system. Others (5, 6) have analyzed the
system influence on IAQ.
Although the ventilation solutions for living building sector have been more widely
analyzed it is important to provide the solutions also for such unclassified buildings as
military barracks, shooting ranges or armories. As there is a strong potential to signifi-
cantly reduce energy consumption also for them. For example shooting ranges have a
need for large amounts of ventilation air and therefore consume a lot of energy however
according to some studies (7) state that in case when conventional ventilation methods
are used it is not possible to obtain suitably low concentrations of harmful substances
in indoor shooting ranges and only a low turbulence displacement ventilation system
provides the correct conditions for rapid conveyance of harmful substances to the ex-
traction outlets in the area of the bullet trap. This means that a special attention must be
paid in choosing the exact solution.
The paper presents the findings of calculation results of performed cost analysis of
different ventilation solutions to determine the most feasible solution for longer running
time periods.
2 Methods
A calculation to determine the installation costs of various ventilation systems and their
annual running costs is performed in this paper. The comparison is made for typical
apartment building located in Latvia and Estonia. The method to achieve this is based
on following steps: Determining the necessary ventilation air volumes for each country;
Designing various ventilation system types for an apartment; Estimating construction
costs of ventilation systems; Performing life cycle costs analysis for each ventilation
system including installation costs, annual maintenance and necessary energy for heat-
ing and electricity.
2.1 Description of case building
All further calculations are based on a chosen case study building. The building type is
a multi-apartment building with 5 stories and 30 flats for each staircase section. The
3
ceiling height is 2.5 m. In building two types of apartments are present. 25 apartments
in each staircase are one bedroom (living area 35m
2
) while five apartments have two
bedrooms (living area 47 m
2
). The ventilation volume is calculated for each type of flat
and the total ventilation volume necessary for one staircase section.
To determine the design ventilation rate a calculation of both supply and exhaust
was performed. Afterwards the largest value was applied as a design value for each flat
type. In Estonia multi-apartment building exhaust airflow can be lower if required sup-
ply airflow is guaranteed. Knowing the ventilation air volume for the each flat the air
for whole staircase section can be calculated. It involves multiplying the calculated
ventilation air volume of one apartment with the number of apartments located in one
buildings section (staircase) and with the number of stories, in this case five. This is
necessary as the centralized AHU unit could serve each staircase separately therefore
dividing building into smaller sections.
For all ventilation design cases the general rule was to supply the air in the bedrooms
and living rooms while there are two spate exhaust systems- in bathroom and kitchen.
The entrance area will be ventilated with the transfer air.
Table 1. Calculated ventilation air volumes for Latvian and Estonian case study building
Room
Nr. Room type
Latvia Estonia
Supply air
m
3
/h
Exhaust air
m
3
/h
Supply air
m
3
/h
Exhaust air
m
3
/h
1 Bedroom 55 (90 for 2-
room apartment)
- 50 -
2 Kitchen - 90 - 22 (30 for 2-
room apartment)
3
Bathroom
-
50
- 54
4
Storage
-
-
- 10
Total for an apart-
3
/h)
55 (90) 140 50 86
Total for whole stair-
case section
(m
3
/h)
6 · 5 · 140 = 4200 (5 · 86 + 119) · 5=2745
2.2 Design examples of ventilation systems
To prepare the cost analysis between the most common ventilation system types they
all were fully designed for an apartment. The analyzed ventilation types included: nat-
ural ventilation by openable windows and natural exhaust (see Fig. 1), natural ventila-
tion by having inlet valves and natural exhaust (see Fig. 1), hybrid type ventilation by
having inlet devices in walls and mechanical exhaust (see Fig. 2), decentralized me-
chanical supply and exhaust with heat recovery (room based heat recovery) (see Fig.
2), decentralized mechanical supply and exhaust with heat recovery (apartment based
heat recovery) (see Fig. 3), centralized mechanical supply and exhaust with heat recov-
ery (see Fig. 3). The shown air volumes in all figures are for case of Latvia as it had the
higher necessary ventilation volumes according to regulations.
In Fig. 1 two natural ventilation solutions are showed. They are still very common
for existing, non-renovated buildings in Latvia and Estonia. The air supply through
4
openable windows or building cracks is the supply type that was foreseen in Soviet time
buildings while air supply through special air inlets is usually designed for renovation
projects of such buildings.
Fig. 1. Natural ventilation system through openable windows and exhaust (left); Natural ventila-
tion system through air inlets and exhaust (right)
For each ventilation type, a specification is provided to show the necessary elements
and prices of them. The specification does not include fittings, mounting elements or
work price. To compensate this, final cost of the system is assumed to be higher by 10
to 30% depending on the predicted extra elements. These values are later used to com-
pare the overall installation and running costs between various solutions.
Table 2. Specification of ventilation system through openable windows and natural exhaust
Name Size Units Quantity
Average price in
EU for one unit
(EUR)
Extract grille
200x100
mm
Pcs.
1
17.00
Extract grille
200x200
mm
Pcs.
1
20.00
Duct
Ø2
00 mm
m
2
1.90
Duct Ø160 mm m 3 1.50
Total cost with 30 % added
60.00
Table 3. Specification of ventilation system through air inlets and natural exhaust
Name Size Units Quantity
Average price in
EU for one unit
(EUR)
Supply vents
Ø
160 mm
Pcs.
2
120.00
Extract grille
200x100
mm
Pcs.
1
17.00
Extract grille
200x200
mm
Pcs.
1
20.00
Duct
Ø
200 mm
m
2
1.90
Duct
Ø
160 mm
m
3
1.50
Total cost with 30 % added
370.00
5
Fig. 2. Hybrid type ventilation system with supply through air inlets and mechanical exhaust
(left); Decentralized ventilation system with room based mechanical supply and exhaust with
room based heat recovery (right)
The left figure above shows the most commonly used ventilation system in newly built
objects in Latvia and Estonia as it is relatively cheap and provides reliable ventilation
volume with mechanical extract ventilators. In more advanced cases the extract duct is
equipped with roof ventilator and a special extract device that evens the ventilation
volume by compensating the natural stack effect.
Table 4. Specification of hybrid type ventilation system with supply through air inlets and me-
chanical exhaust
Name Size Units Quan-
tity
Average price in
EU for one unit
(EUR)
Supply vents
Ø
160 mm
Pcs.
2
120.00
Domestic type extract fan
Ø
100 mm
Pcs.
1
70.00
Domestic type extract fan
Ø
200 mm
Pcs.
1
90.00
Duct
Ø
125 mm
m
2
1.20
Duct
Ø
100 mm
m
3
0.90
Total cost with 30 % added
525.00
Table 5. Specification of decentralized ventilation system with room based mechanical supply
and exhaust with room based heat recovery
Name Size Units Quantity
Average price in
EU for one unit
(EUR)
Paired decentralized ventila-
tion devices (50 and 90 m
3
/h)
- Pcs. 4 485.00
Control unit
-
Pcs.
1
320
Domestic type extract fan
Ø
100 mm
Pcs.
1
70.00
Duct
Ø
100 mm
m
2
0.90
Total cost with 10 % added
2560.00
6
Fig. 3. Decentralized ventilation system with apartment based mechanical supply and exhaust
with apartment based heat recovery (left); Centralized ventilation system with building based
mechanical supply and exhaust with heat recovery (right)
In Fig. 3 fully mechanical ventilation systems with controlled supply/exhaust ventila-
tion volumes are shown. Such type of system grants the highest precision in setting the
necessary ventilation volume as well as provides the possibility to set up daily ventila-
tion schedule which reduces the energy consumption. The mechanical ventilation sys-
tem can either be located in each apartment or made centralized in AHU located in attic.
Table 6. Specification of decentralized ventilation system with apartment based mechanical sup-
ply and exhaust with apartment based heat recovery
Name Size Units Quantity
Average price in
EU for one unit
(EUR)
AHU (140 m
3
/h)
-
Pcs.
1
1800.00
Air intake grill
200x200
mm
Pcs.
1
40.00
Extract air roof
hood
Ø160 mm Pcs. 1 200.00
Air supply grill
200x
100 mm
Pcs.
2
17.00
Air exhaust grill
200x100 mm
Pcs.
1
17.00
Air exhaust
valve
Ø100 Pcs. 1 5.00
Duct
Ø
160 mm
m
10
1.50
Duct
Ø
125 mm
m
4
1.20
Duct
Ø
100 mm
m
7
0.90
Silencers Ø100 mm/
L=1000mm
Pcs. 4 75.00
Total cost with 20 % added
2900.00
7
Table 7. Specification of Centralized ventilation system with building based mechanical supply
and exhaust with heat recovery
Name Size Units Quantity
Average price in
EU for one unit
(EUR)
For whole building
Centralized AHU
(4200 m
3
/h)
- Pcs. 1 9500.00
Air intake grill
Ø560 mm
Pcs.
1
100.00
Extract air roof
hood
Ø560 mm Pcs. 1 700.00
Silencers Ø560 mm/
L=1000mm
Pcs. 4 250.00
Duct
Ø560 mm
m
20
17.30
For apartment
Air supply valve
Ø100 mm
Pcs.
2
5.00
Air exhaust grill
200x100 mm
Pcs.
1
17.00
Air exhaust valve
Ø100 mm
Pcs.
1
5.00
Duct
Ø160 mm
m
3
1.50
Duct
Ø125 mm
m
4
1.20
Total cost with 30 % added*
560.00
*The total cost includes the cost of all units located in the apartment and 1/30 of
whole price for whole building units, as there are thirty apartments that would be served
by the AHU.
3 Results
The results are based on the comparison of calculation results of economic analysis for
designed ventilation systems as cost analysis has a major importance in choosing the
appropriate ventilation system. To compare cost efficiency of different ventilation sys-
tems the following factors was taken into account: installation costs, maintenance costs,
heating costs to heat up the ventilation air during heating period, electricity consump-
tion for powering the ventilation system, assuming that the ventilation system works
continuously through whole year. The cost comparison is done for one staircase of pre-
viously described case study building and with following assumptions:
1)
Cost of installing all necessary equipment;
2)
Annual maintenance cost for all necessary equipment for whole staircase section;
3)
Cost of heating supply air for one heating season assuming the Heating degree
days for base indoor temperature of +21,0°C for Latvia 4263, for Estonia 5656 (8) and
assuming that the heating occurs by district heating system with following costs - for
Latvia 55.55 EUR/MWh; for Estonia 65 EUR/MWh;
4)
Annual cost of all energy necessary to power the ventilation devices for whole
staircase apartment assuming that they are powered by electricity with the cost of 0.169
EUR/kWh for Latvia; 0.15 EUR/kWh for Estonia.
8
Table 8. Comparison of installation and running costs for Latvian / Estonian case study (upper
numbers are for Latvia, lower for Estonia)
Type of ventilation
system
Installa-
tion
costs
1)
(EUR)
Mainte-
nance
costs
2)
(EUR)
Heating costs
3)
(EUR)
Powering
costs
4)
(EUR)
Total An-
nual
costs
(EUR)
Natural by opening
windows and natu-
ral exhaust
1800 -
-
8005
8110
-
-
8005
8110
Natural by having
inlet valves and
natural exhaust
11 100 300
450
8005
8110
-
-
8305
8560
Hybrid by having
inlet devices in
walls and mechani-
cal exhaust
15 750 450
600
8005
8110
1155
1025
9610
9465
Decentralized me-
chanical supply and
exhaust with heat
recovery (room
based system)
76 800 750
750
1600 (eff. 0,80)
1620 (eff. 0,8)
535
580
(0,16
W/m
3
/h)
2885
2950
Decentralized me-
chanical supply and
exhaust with heat
recovery (apart-
ment based
system
)
87 000 1050
1500
1200 (eff. 0,85)
2030 (eff. 0,75)
3455
(SFP 1.0)
3210
(SFP 1.6)
5705
6740
Centralized me-
chanical supply and
exhaust with heat
recovery
16 760 1000
1000
1600 (eff. 0,80)
2030 (eff. 0,75)
2070
(SFP 1.2)
4010
(SFP 2.0)
4670
7040
Fig. 4. Life cycle cost comparison of various ventilation solutions for 10 year period for Latvia
The Fig. 4 represents the life cycle cost analysis for 10 year period of different ven-
tilation scenarios in case of Latvian ventilation volumes and climate.
0
20000
40000
60000
80000
100000
120000
140000
160000
0 2 4 6 8 10
Life cycle costs (EUR)
Year
Natural by opening windows and
natural exhaust
Natural by having inlet valves and
natural exhaust
Hybrid by having inlet devices in
walls and mechanical exhaust
Decentralized mechanical supply
and exhaust with heat recovery
(room based system)
Decentralized mechanical supply
and exhaust with heat recovery
(apartment based)
Centralized mechanical supply and
exhaust with heat recovery
9
4 Discussion
The results show that different ventilation solutions can very noticeably vary in installa-
tion and running costs. In general it can be concluded that the systems can be divided in
three price ranges – the simplest one is just having natural exhaust channels and supply
through windows (~1800 EUR), the middle price range includes more advanced systems
such as natural system with inlet valves, hybrid system with mechanical exhaust and cen-
tralized ventilation system (~15 000 EUR), while the most pricy systems are either room
based or apartment based decentralized ventilation systems (80 to 90 thousand EUR).
However these costs must be looked at in combination with annual running and mainte-
nance costs. For this three different levels also stand out – the most cost efficient is the
room based mechanical system, the second are the centralized and apartment based full
mechanical ventilation systems as they have high heat recovery, and lastly the most inef-
ficient systems are the ones without heat recovery.
The Figure 4 shows that in general the most economically feasible choice would be
to use centralized, building based ventilation system with one AHU for each staircase.
In this case the costs of installation and maintenance would be reduced by spreading it
evenly through all the occupants. Also the maintenance would be lower as each flat
only needs to take care of one unit. The second most economical system is just having
natural ventilation through openable windows. Although in such case no heat is recov-
ered but there is no need for electricity or maintenance.
However it must be noted that to make the final decision when choosing ventilation
type not only economical factor must be accounted for as the most important task of
the ventilation system is to provide good indoor climate even if it means larger invest-
ments during construction phase. This means that additional factors like automation
level, human comfort, noise generation from ventilation system or outside, possibility
to filter incoming air, etc. must be introduced to account for this.
Also the existing experience of Estonia shows that room based ventilation is not
recommended as it generates high noise, often not enough space in external wall is
present, the wind flows through the device and the actual efficiency is smaller than
specified in technical data. This has led to trend to avoid such solution.
5 Conclusions
The results for case study building showed that the design ventilation air volume be-
tween Latvia and Estonia for the specific multi apartment building can vary about 1,5
times - 4200 m
3
/h in case of Latvia, while for Estonia 2745 m
3
/h.
Installation cost for various ventilation system types where calculated and the results
showed that the cost can vary from 1800 EUR for simple natural exhaust system up to
87 000 EUR if each flat has a separate full supply/exhaust ventilation system with AHU.
The more common solutions as hybrid or centralized mechanical ventilation systems
would cost around 15 000 EUR per staircase section.
The ventilation running costs that include maintenance, heating and electricity can
vary from 3000 EUR in case of room based decentralized ventilation system up to 9500
10
EUR in case of hybrid type ventilation system. The running cost between Latvia and
Estonia are quite similar as the necessary ventilation volume for Estonia is lower but
the price for heating energy is higher. According to cost simulation for 10 year running
period for the analyzed ventilation system the results showed that the most cost-effec-
tive systems is the centralized full mechanical supply/exhaust system.
6 Acknowledgements
This study was supported by European Regional Development Fund project
Nr.1.1.1.1/16/A/048 “Nearly zero energy solutions for unclassified buildings”.
This research was supported by the Estonian Centre of Excellence in Zero Energy
and Resource Efficient Smart Buildings and Districts, ZEBE, grant TK146 funded by
the European Regional Development Fund, and by the Estonian Research Council with
Institutional research funding grant IUT1-15.
This work has been supported by the European Regional Development Fund within
the Activity 1.1.1.2 “Post-doctoral Research Aid” of the Specific Aid Objective 1.1.1
“To increase the research and innovative capacity of scientific institutions of Latvia and
the ability to attract external financing, investing in human resources and infrastructure”
of the Operational Programme “Growth and Employment” (No.
1.1.1.2/VIAA/1/16/033).
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... Analysing the research and tests regarding microclimate in non-residential buildings conducted by researchers of RTU Department of Heat Engineering and Technology [21], [22], it is assumed that a ventilation machine works 24 hours a day during the winter (3 months), and 16 hours a day during other seasons -6560 hours per year; air-conditioning works during the summer for an average of 14 hours a day during 3 months or 1260 hours per year. Such an operation can be suitable for retail trade buildings, office buildings and hospitals, for educational institutions operating hours per year can be lower. ...
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Investigation shows that in apartment buildings with passive stack ventilation the indoor air quality (IAQ) changes greatly. In the investigated apartment building the relative humidity level in bedrooms of different apartments varied greatly, from 20 to 72% in the autumn period. In the winter period the RH maximum reduces to 55%. High relative humidity is accompanied by problems of mould and a very low relative humidity level causes an unpleasant feeling when people get up in the morning. Greatly varying was also the morning CO2 level in bedrooms of different apartments, from 1000 ppm to 4200 ppm, the latter being quite critical. Higher levels of CO2 concentrations were first of all in bedrooms with renovated windows and with doors closed. By simulation the smallest is the energy consumption in the case of supply-exhaust ventilation. The results of the simulation of indoor climate are close to the results of the data recorded. The indoor climate of residential buildings is greatly affected by the arrangement of air change which in its turn is influenced by the external climate of the country.
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Complete knowledge about habits of the occupants, including their opinions regarding ventilation systems is an important condition for reducing the consumption of natural resources and improving indoor comfort. In addition, uncomforted occupants tend to take measures to improve their situation, which may increase energy consumption. Advanced thermal models for buildings can perhaps predict interactions between the IAQ determinants, e.g. energy consumption, ventilation and comfort, but do not take into account the behavior of residents. By questionnaires and physical measurements this study evaluated dwellings equipped partly with centralized and partly with decentralized ventilation systems with heat recovery. This field study involved two post-occupied residential buildings situated in the city of Esch-sur-Alzette, Luxembourg, during spring season 2015. Thus, both the physical measurements and questionnaires were considered. The results obtained demonstrated that more than 80% of the residents were satisfied and the perceived IAQ was judged “normal”, “good” or even “very good”. Furthermore, the measurements performed detected in some cases malfunction of ventilation devices, wherefore the occupants were unable.
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This work performs a comprehensive characterization of the relation between energy use and ventilation rates in both residential and services buildings in the diversity of European climates. Through detailed building simulation, a sensitivity analysis was performed considering four building types (detached house, apartment, office and school), three climates/locations (Helsinki, Paris and Lisbon), three heating and cooling setpoints settings, four air-flow control strategies, usage of heat recovery coupled with four different building airtightness conditions, and three ranges of humidity control. The impacts of changing ventilation rate (ICV) were determined for each case as being the slope of the energy needs as function of the ventilation rate, in the range of 0–50 m3/(h person). The energy results, assessed through dynamic building simulation, show that changing ventilation by 1 m3/(h person) with current practice systems has an impact in total HVAC-related final energy demand between 0.3 and 0.6 kWh/(m2 year) depending on building type and location. However, with advanced systems the ICV values could become close to 0.1 [kWh/(m2 year)]/[m3/(h person)] in most cases analyzed. These results can be used to assess the energy impacts of IAQ polices, including hypothetical trade-offs between health and energy or different degrees of use of the precautionary principle.
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In this study, we analyze the impact of ventilation heat recovery (VHR) on the operation primary energy use in residential buildings. We calculate the operation primary energy use of a case-study apartment building built to conventional and passive house standard, both with and without VHR, and using different end-use heating systems including electric resistance heating, bedrock heat pump and district heating based on combined heat and power (CHP) production. VHR increases the electrical energy used for ventilation and reduces the heat energy used for space heating. Significantly greater primary energy savings is achieved when VHR is used in resistance heated buildings than in district heated buildings. For district heated buildings the primary energy savings are small. VHR systems can give substantial final energy reduction, but the primary energy benefit depends strongly on the type of heat supply system, and also on the amount of electricity used for VHR and the airtightness of buildings. This study shows the importance of considering the interactions between heat supply systems and VHR systems to reduce primary energy use in buildings.
Ventilation in indoor shooting ranges
  • G Mirbach
Mirbach, G.: Ventilation in Indoor Shooting Ranges. In: Proceedings of the Workshop on Indoor Shooting Ranges, pp. 105-112, Rome, Italy (2005)
Indoor Air Quality and Energy Efficiency in Multi-Apartment Buildings before and after Renovation
  • I Dimdina
  • A Lešinskis
  • E Krumiņš
  • V Krumiņš
  • L Šnidere
  • V Zagorskis
Dimdina, I., Lešinskis, A., Krumiņš, E., Krumiņš, V., Šnidere, L., Zagorskis, V.: Indoor Air Quality and Energy Efficiency in Multi-Apartment Buildings before and after Renovation. In: 12th International Conference on Air Distribution in Rooms "Roomvent 2011": Book of Abstracts, pp. 30-30. Norway, Trondheim (2011)