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International Journal of Latest Technology in Engineering, Management & Applied Science (IJLTEMAS)
Volume VII, Issue VI, June 2018 | ISSN 2278-2540
www.ijltemas.in Page 53
Computer Program for Cooling Load Estimation and
Comparative Analysis with Hourly Analysis Program
(HAP) Software
Saifullah Zaphar1, Tekletsadik Sheworke2
1.2Thermal Energy & Automotive Engineering, School of Mechanical & Industrial Engineering, Dire Dawa University, Dire
Dawa, Ethiopia
Abstract—Energy efficiency building design the cooling load
estimation plays a vital role because now a day’s major part of
the power is consumed to run the heating ventilation air
conditioning (HVAC) system. Hence to design and development
of cooling load software is mandatory to incorporate the energy
efficiency features to reduce the power consumption and
accurate and fast results. Previously cooling load estimation was
done manually which is quite tedious, complex, time consuming
and liable to error due to complex architectural design. The
present endeavor to design and develop a software which has an
edge over the various other complexes and costly software
available in market. The present software is enhanced user
friendly and minimum data input with accurate results obtained.
This software is based on the carrier data book used for cooling
load estimation based on cooling load transfer and solar heat
gain factor method. The programming language has been done
in Visual Basic 6.0 and Microsoft Access has been used to create
the data base. The approach in the present work is divided in
three modules and prepares the individual algorithm, flow chart,
and individual form design for each part. Step by step the data
input will be given as per the architecture design and finally the
result sheet will come after finishing all data input. The testing &
validation of this software is done by solving one sample project
with this software and carrier hourly analysis program software
(HAP v 4.90) which is available in world wide market. The
comparative results obtained by both of the software are so close
and accurate and finally the level of accuracy of present software
is 98.1%.
Key Words: Ventilation, Hourly analysis program, cooling load,
solar heat gain, Air Conditioning etc
I. INTRODUCTION
uman civilization came to existence, human‟s need of
comfort, satisfaction and luxury increased manifolds.
The advent of air-conditioning system played an important
role in this direction of human need. There is definite range of
temperature and humidity within which best human efficiency
and comfort can be obtained. HVAC engineers aim to provide
these conditions with optimum saving of energy by selecting
the correct sized equipment with minimum cost. From
engineering point of view, determining the cooling load of
HVAC system is the most .Important task. Cooling/heat load
of building consists of outside heat transmission through
building envelopes as well as internal loads due to occupancy,
electrical appliances and outside air. It is most importance in
cooling/heating load calculation, to know the exact amount of
these load components. Estimated load makes a basis of
selecting different equipments such as chillers; air handling
units, boilers, cooling towers, pumps, fan coil unit etc. in
actual practice intelligent HVAC system has been developed,
where the system adjusts automatically according to the load
conditions. These are highly energy efficient HVAC
systems.[1] carriers hourly analysis program (HAPv4.90) is
commercial software that forms the cooling/heating load
calculation on hourly basis which assists engineers in
designing HVAC systems for all kind of buildings. [2]Air-
conditioning is utilized to supply a controlled atmosphere to
public buildings such as offices, halls, homes, and industries
for the comfort of human being or for the proper performance
of some industrial processes. Full air-conditioning implies that
the purity, movement, temperature and relative humidity of
the air be controlled within the limits imposed by the design
specification. For any air conditioning system to perform
satisfactorily, equipment of the proper capacity must be
selected based on the instantaneous peak load requirements.
[3] The HAP program can be used for any building design to
calculate the load and select the systems.
Cooling load estimation through computer application sounds
reasonable to replace tedious and time consuming manual
methods. To achieve this computer automation, software is
developed using “visual basic 6.0” programming language
tool and “MS access” used as a data base system.
There are many software‟s developed for HVAC system
design etc. all software has some advantages and limitations.
The present work focuses on the limitations of other software
and aim at their limitation.
Me mate HVAC software [4] is available in the market in
which the distinctive feature is calculation of cooling and
heating load in unlimited number of spaces. Me-mate HVAC
uses a traditional approach to HVAC design, with
computerized calculations and drafting. White rose [5] is
another software, in which data globalization facilities for the
H
International Journal of Latest Technology in Engineering, Management & Applied Science (IJLTEMAS)
Volume VII, Issue VI, June 2018 | ISSN 2278-2540
www.ijltemas.in Page 54
rapid entry of data psychometric analysis of room, heat gains
and sensible heat ratio, integrating product moisture loss
calculations for sensible to latent heat adjustment built-in
solar aspect temperature difference adjustment of walls and
ceiling exposed to external ambient condition are taken care
of. Next focus on the elite software [6] for HVAC system is in
two parts CHVAC and RHVAC. CHVAC software of elite
quickly and accurately calculates the maximum heating and
cooling loads for commercial buildings and RHVAC use for
residential buildings. The cooling loads can be calculated with
either the cooling load temperature difference (CLTD) method
or the new radiant time series (RTS) method. The program
allows an unlimited number of zones, which can be grouped
into as many as 100 air handling systems. CHVAC
automatically looks up all cooling load and correction factors
necessary for computing loads. In addition, it can look up
outdoor design weather data for over 2000 cities located
around the world. There is also provision for editing the
weather data as well as adding data for other cities.
A. Objective of present work
It is well known that the greater the accuracy in finding out
the cooling load of the building envelope throughout the year,
the more energy can be saved. so it is very important to know
which methods give the best cooling effect. This purpose can
be served by comparing the results obtained by different
methods. Various methods have been developed and used for
this purpose for last few decades.
For energy savings and costs concerns, both fixed and running
costs should be considered.
Present work aims at developing the computer operated
comprehensive software to estimate cooling load. Software
must be user friendly and should involve minimum operation
time. cooling load estimation by the present software is
compared with the other commercial software.
Ultimately after going through all the available software it can
be concluded that these software‟s require skilled operator.
These software‟s are more versatile and have lot of facilities
but the computational time is more. as such they are not very
much user friendly. The present software is an effort to take
care of all such limitations. The software is based on visual
basic and MS access. Visual basic is the programming
language and MS access is the data base system. All data are
taken from carrier hand book [7].
B CLTD method/SCL /CLF method
This method is used for the manual heat load or cooling load
calculation on hourly basis. The CLTD method makes use of
cooling load temperature difference in the case of walls, roofs,
partition wall. Solar cooling load factor (SCL) in the case of
solar heat gain through windows glass and cooling load factor
vary with time and are function of environmental conditions
and building parameters.
Cooling Loads are classified in six categories.
i. Heat gain by transmission medium ( Through glass
only sensible load)
ii. Heat gain by solar energy(Through Walls and Roof
only sensible load)
iii. Heat gain by other transmission medium ( Through
partition wall, partition glass, ceiling and floor
sensible load)
iv. Infiltration and ventilation air load (both sensible and
latent load)
v. Internal Load (Through People ,appliances ,lighting
etc both sensible and latent load)
vi. Safety factor and supply duct heat loss and duct
leakage loss both sensible and latent
C Mathematical Formulations
i) Heat gain by transmission medium (Through glass only
sensible load) this is the heat gain due to transmission of solar
energy radiation through transparent part of the building in all
directions through glass
Q rad = Ag(SC)(SHGF)(CLF) ------------------------ [ I ]
Ag= Area of the glass
SC = Shading coefficient
SHGF = solar heat gain factor for externally shaded windows
CLF = cooling load factor, w/ (sq.m-k)
Q = A (SC) SCL
ii) Heat gain by solar energy
(Through Walls and Roof only sensible load)
q = UA (CLTDC)------------------------------------------- [II]
U = Design heat transfer coefficient for roof or wall, W/(sq.m-
k).
A = Area of roof, wall, or glass, calculated from building
plans, sq. m.
The tabulated CLTD must be corrected for the different inside
and outside temperature and daily range when the conditions
differ. This can be done using the following equation.
CLTD corrected = CLTD + (78 + ti) + (tom – 85)
where,
ti = Actual inside dry bulb temperature, 0c
tom = to– dr/2, Mean outside design dry bulb temperature, 0c
where,
to = Outside design dry bulb temperature, 0c
dr = Daily Range, 0c
Finally
Q wall = U wall *A wall * T Equivalent Temperature difference ------------- (III)
International Journal of Latest Technology in Engineering, Management & Applied Science (IJLTEMAS)
Volume VII, Issue VI, June 2018 | ISSN 2278-2540
www.ijltemas.in Page 55
Q roof= U roof *A roof* T Equivalent Temperature difference ------------- (IV)
U Wall and Equivalent Temperature difference values can be taken from
carrier hand book tables
iii) Heat gain by other transmission medium (Through
partition wall, partition glass, ceiling and floor sensible load)
Cooling load from partition walls and other glass
Q partition wall=UA(to – ti)
Q Other glass=UA(to – ti)
Cooling load from ceiling and floor
Q Ceiling = U*A*[ (to – ti) -5]----------------------------------(V)
Q Floor = U*A*[ (to – ti) -5]----------------------------------(VI)
Where,
U = design heat transfer coefficient for partition walls and
windows
A = area of partition walls, other glass, ceiling ,floor
calculated from building Plans
to = temperature in adjacent space
ti = inside design temperature (constant) in conditioned space
iv) Infiltration air load (both sensible and latent load)
Q sensible = CFM *DBT Difference* 1.08 --- ----------(VII)
Q latent = CFM (ωo - ωi)* 0.68------- ---------------(VIII)
Where CFM= crack length* leakage rate CFM/ft + CFM/door
* No‟s of doors
Q infiltration total=Q sensible +Q latent
to, ti = outside, inside air temperature, °C
ωo, ωi = outside, inside air humidity ratio, kg (water)/kg (dry
air)
Ventilation Air load estimation
CFM or Fresh air supply from outdoor= (CFM/person * No‟s
of persons) + (CFM/sqft * area in sq ft)
v) Internal Load (Through People, appliances, lighting etc
both sensible and latent load)
Internal Heat gain by people
Qs = N(Sensible heat gain/person)--------------------(IX)
Ql = N(Latent heat gain/person) -------------------- -(X)
N = number of people in space, from best available source.
CLF = cooling load factor, by hour of occupancy
Internal Lights load
Qlight = (N)(W) (BF) * 3.4----------------------------(XI)
N = number of lights in space.
BF = Ballast factor, 1.0 for incandescent bulb and 1.25 for
fluorescent light
W = watts input from electrical plans or lighting fixture data
Appliances and equipments
Qe = (N)(W)(CLF) -------------------------------------(XII)
N = number of appliances and equipments in space.
W = watts input from electrical plans
CLF = cooling load factor, by hour of occupancy and room
furnishings; 1.0 for 24 hours of operation
vi) Safety factor and supply duct heat loss and duct leakage
loss both sensible and latent
Leak loss through duct = 5 % of TRSH
Leak loss latent through duct =5 % of TRLH
Total sensible heat loss= safety factor+ Supply duct
heat gain+ supply duct leak loss + fan heat gain
Total latent heat loss= safety factor + supply duct leak loss
Outdoor air heat loss= return duct heat gain+ return duct leak
heat gain +H.P pump heat gain+ Pipe loss
Approximately total (5%-10%) losses in both sensible and
latent heat gain.
Fig 1. Flow Chart representation for hourly basis cooling load estimation
D .Methodology:
The approach in the present work is divided in three modules
and prepares the individual algorithm, flow chart, and
individual form design for each part. For cooling load
International Journal of Latest Technology in Engineering, Management & Applied Science (IJLTEMAS)
Volume VII, Issue VI, June 2018 | ISSN 2278-2540
www.ijltemas.in Page 56
estimation we divide the work into three parts. Each part has a
separate form, and for each separate form separate logic and
programming is done. This software is very reliable, versatile,
user friendly easy to operate, involving less computation time,
and minimum error. The main property of this software is that
it is optional and with the minimum input data maximum
output can be achieved, it gives online help at critical stages
for the type of load. At the end of proper execution of
program, it gives the final results, which have complete
description about the cooling load estimation
For finding the cooling load estimation, twelve forms has
been design with separate algorithm and flow chart.
Twelve step of cooling load estimation with different forms
1) Selection of CFM ventilation
2) Outside and inside design condition
3) Solar heat gain through glasses
4) Solar heat gain through wall
5) Solar heat gain through other transmission medium (all
glass)
6) Solar Heat gain through other transmission medium
(partition wall)
7) Solar heat gain through other transmission medium
(ceiling & floor)
8) Sensible heat gain by infiltration & Ventilation
9) Sensible internal heat load (people & apparatus)
10) Latent internal heat gain (people)
11) Apparatus dew point temperature selection
12) Final result sheet of cooling load Estimation
For Example CFM Ventilation Calculation Prompts (Form1)
design based on algorithm, flow chart and Form 1 design.
ALGORITHM: FORM-1
STEP 1 START
STEP 2: INPUT JOB, PURPOSE, AREA, HEIGHT, NO
OF AIR CHANGE, & NO OF PERSON
STEP 3: CALCULATE CFM1 BY AREA= (VOLUME
OF AREA‟ X „NUMBER OF AIR CHANGE‟) / 60
STEP 4: CALCULATE CFM2 BY PERSON = 20 X „NO OF
PERSON‟
STEP 5: IF CFM1>CFM2 THEN CFM = CFM1ELSE CFM =
CFM2
STEP 6: PRINT„CFM VENTILATION‟ CFM
STEP 7: STOP
FLOW CHART- FORM-1
Fig 2. Flow Chart Representation for CFM Selection
International Journal of Latest Technology in Engineering, Management & Applied Science (IJLTEMAS)
Volume VII, Issue VI, June 2018 | ISSN 2278-2540
www.ijltemas.in Page 57
FORM -1 Design
Fig -3 Form Design
E Testing and Comparative Analysis
It was envisaged by the present authors to write a
computer program on the basis of this cooling load
estimation form and compare the results with the
commercially available hourly analysis software(HAPv 4.9)
Fig. 4: A Sample Residential House Layout
Consider the location of the project is New Delhi. The
required cooling load design is obtained at the peak period of
summer. The result obtained by the present software and
careers hourly analysis program (HAP v 4.90) .The
comparative analysis is done on the basis of results obtained
in both of the cases.
1. Design Data: Source 2001ASHRAE Hand Book
Project Name: Prakriti
Purpose: Residential House
Whether Station: New Delhi, India, Asia Pacific
Peak Month and solar time: June, 13:00 PM
Latitude: 28.6 Degree North
Longitude: 77.2 Degree East
Elevation: 708 feet
Summer outside Design Condition,
Dry Bulb Temperature (DBT): 1070 F
Wet Bulb Temperature (WBT): 720F
Summer daily range (DR): 21.6 0 F
Relative Humidity (RH) value: 20%
Inside design, DBT: 750F
Inside RH value: 50%
Cooling Coil temperature
Apparatus Dew Point Temperature (ADP):550F
2 Building Survey:
There is no existing building in front or behind of the
building which means that the sides of the building are
directly open to atmosphere and the building is north facing.
2.1 Case study 1: Hall Room Results by HAP v 4.90, 2014
To test the software (estimate cooling load) a model room
with following characteristics was assumed:
Room Area: 231 Square feet
Height:10 feet
Roof: 100 mm light weight concrete without
suspended ceiling.
Wall: Group 9” Face Brick + Air Space
East wall, West wall and North wall as sunlit wall
and South wall as partition wall.
Windows = Sunlit, 13 mm clear ordinary glass with
U = 3.0 W/m2 C
Light = 25W/m2
of floor area
ACH (Air Change/hour) = 1/hour
Hall room, accommodating 3 people
International Journal of Latest Technology in Engineering, Management & Applied Science (IJLTEMAS)
Volume VII, Issue VI, June 2018 | ISSN 2278-2540
www.ijltemas.in Page 58
TABLE-I Air System Sizing Summary for Fan Coil Unit (FCU) Selection, Hall Room
TABLE 2 Cooling Load Summary for Fan Coil Unit (FCU) Hall
International Journal of Latest Technology in Engineering, Management & Applied Science (IJLTEMAS)
Volume VII, Issue VI, June 2018 | ISSN 2278-2540
www.ijltemas.in Page 59
TABLE-3 Result Summary Sheet Obtained by Present Software for Hall (Case Study -1)
2.2 Case study-2 Bed Room Results by HAP v 4.90, 2014
To test the software (estimate cooling load) a model room
with following characteristics was assumed:
Room Area: 90 Square feet
Height:10 feet
Roof: 100 mm light weight concrete without
suspended ceiling.
Wall: Wall: Group 9” Face Brick + Air Space
East wall & south wall as sunlit wall and others wall
as partition wall.
Windows = Sunlit, 13 mm clear ordinary glass with
U = 3.0 W/m2 C
Light = 25W/m2
of floor area
ACH (Air Change/hour) = 1/hour
Hall room, accommodating 1 people
TABLE-4 Air System Sizing Summary for Fan Coil Unit (FCU), Bed Room
International Journal of Latest Technology in Engineering, Management & Applied Science (IJLTEMAS)
Volume VII, Issue VI, June 2018 | ISSN 2278-2540
www.ijltemas.in Page 60
TABLE-5 Result Summary Sheet Obtained by Present Software for Bed Room.( Case Study-2)
TABLE-6 Air System Design Load Summary Fan Coil Unit (FCU), Bed Room
International Journal of Latest Technology in Engineering, Management & Applied Science (IJLTEMAS)
Volume VII, Issue VI, June 2018 | ISSN 2278-2540
www.ijltemas.in Page 61
TABLE-7 Comparative Summary Results:
Case study 1-results and case study 2 -results obtained by carriers HAP v4.5 program software and the present software.
S.No
Design parameters
Case study 1 Hall Room Results
Case Study 2 Bed Room Results
HAP v 4.5
Present Software
HAP
V 4.5
Present Software
1
Total Coil Load (TR)
2.4
2.33
1
0.92
2
Total CFM Coil
1330
1435
605
492
3
Sensible Heat Factor(SHF)
0.95
0.97
0.96
0.98
4
Coil ADP(0F)
55.2
55
56
56.9
5
ERSH(BTU)
23346
24493.4
10542
10127
6
ERLH(BTU)
1429
818.15
455
239
7
Total Heat,( (BTU)
24775
25311.55
10997
10366
8
Area (Ft2/TR)
94.8
99.14
89.9
97.8
9
BPF
0.1
0.1
0.1
0.1
II. CONCLUSION
In this paper the software is designed to find the cooling load
estimation. To finding the accuracy and validity of the
designed software the comparative analysis is done by
worldwide market existing software tool .i.e. Hourly analysis
program (HAP v 4.90) version, 2014.
As per the tabulated summary sheet (Table -8) following
conclusions have been made.
i. The total cooling load obtained by the present
software for the Hall is 2.33TR and the cooling coil
load obtained by HAP software is 2.4TR after
considering the safety factor the results obtained by
both of the software is almost same.
ii. Other results obtained like Sensible heat factor,
supply CFM, Coil ADP , Effective Room Sensible
Heat(ERSH),Effective Room Latent
Heat(ERLH),Room total heat, Area required per TR,
BPF etc are also somewhat correlated and the results
are almost similar. By present software it is found
that each TR can cover 99.14 square feet of area for
air conditioning of hall while for HAP software it is
found that each TR can cover 94.8 square feet of
area.
iii. In the present software which is more realistic, User
friendly and less time consuming with accurate
results.
III. LIMITATIONS & FUTURE WORK
The present software limitations are that the data is that the
weather data only limited it‟s not based on hourly analysis. As
well as the various energy efficiency factors can incorporate
in this software for designing of energy efficiency HVAC
system design in future.
REFERENCES
[1]. Carrier Corporation, 8th edition 10/2014, Hourly Analysis
Program (HAPv4.90) Quick reference guide, Software system
network, Carrier Corporation. Copyright 1998-2014 Carrier
Corporation.
https://www.carrier.com/commercial/en/us/software/hvac-system-
design/hourly-analysis-program/
[2]. Hani H. Sait, Int.Conference on Sustainable Energy
Information Technology,2013, Journal Volume: 19, pages 636-
645, Estimated Thermal Load and Selecting of Suitable Air-
Conditioning Systems for a Three Story Educational Building.
[3]. Azhar Kareem Mohammed1,Ranj Sirwan Abdullah2, Iyd Eqqab
Maree3, “Comparison between Hand Calculation and HAP
programs for estimating total cooling load for Buildings” ZANCO
Journal of Pure and Applied SciencesThe official scientific journal
of Salahadd in University-ErbilZJPAS (2016), 28 (4); 90-96
[4]. “ME-MATE HVAC Integrated software” for HVAC design and
drafting tools;Copy righted © 1996-2002 by energy and
Mechanical systems consultants, at the Web site
www.memate.com
[5]. “White rose software for computer application for t he design
evaluation and analysis of HVAC systems.Ashrae
standard,www.cbel.com
[6]. “Elite software HVAC loads and energy analysis
programs”www.elitesoft.com/web/hvac/elite_hvac_ndx.html.14th
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