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Mobile HIL Test Bench for Low Cost Radiative Heating and Cooling Collectors

Authors:
  • University of Applied Sciences Stuttgart

Abstract and Figures

This paper presents a mobile hardware-in-the-loop (HIL) test bench that has been developed to simulate a solar assisted cooling and heating system for residential buildings in hot climates. The main component of the system is a low cost uncovered solar collector that is used for the production of night radiative cooling or daytime heating energy (hardware component). The collector was designed for low cost housing projects in Egypt, whose cooling and heating demand was modeled using the program TRNSYS (software component). The design and construction of a mobile HIL test bench is presented together with some performance results from the HIL-tests in cooling mode.
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Mobile HIL Test Bench for Low Cost Radiative Heating and Cooling Collectors
Irina Mitina, Reiner Braun
1
, Antoine Dalibard, Tobias Erhart, Ilyes Ben-Hassine and Ursula Eicker
Centre for Sustainable Energy Technology Research,
University of Applied Sciences Stuttgart HFT Stuttgart,
Schellingstr.24, 70174 Stuttgart, Germany, reiner.braun@hft-stuttgart.de
Abstract
This paper presents a mobile hardware-in-the-loop (HIL) test bench that has been developed to simulate a solar
assisted cooling and heating system for residential buildings in hot climates. The main component of the system is a
low cost uncovered solar collector that is used for the production of night radiative cooling or daytime heating energy
(hardware component). The collector was designed for low cost housing projects in Egypt, whose cooling and heating
demand was modeled using the program TRNSYS (software component). The design and construction of a mobile
HIL test bench is presented together with some performance results from the HIL-tests in cooling mode.
Keywords: HIL test bench, space heating and cooling, solar absorber, radiative cooling
1. Introduction
Low cost renewable heating and cooling systems are of prime importance for developing nations with high
population densities and limited financial resources. As an example, Egypt is one of the fastest growing countries
worldwide, the population increased from 21 million in 1950 to 98 million in 2017 and is currently ranked on place
14 by total population size worldwide. For the year 2050 a total population for Egypt of 153 million it is expected
(UN, 2017). Due to this fast population increase, the state of Egypt is facing many social and economic problems.
Providing decent and affordable housing for the lower and middle class and the adaptation of the energy system will
be two of these challenges for the future.
During the past few years, Egypt has been suffering from recurrent electricity cut-offs, mainly in summer because of
the large cooling demand (Elharidy et al., 2013). The national demand has been exceeding the available produced
power from generation plants since 2011.
Fig. 1: Electricity-shares sold in Egypt (on all voltage levels) according to the purpose of usage 2013/2014 (Egyptian Electricity
Holding, 2014)
Fig. 1 shows the electrical energy consumption distribution among the different sectors in Egypt. The greatest share
of the total nationally generated electricity is consumed in residential buildings (43.4%). When considering only the
medium and low voltage levels, the residential consumption reaches 51.3% of the total energy sold from the national
electricity distribution companies (Egyptian Electricity Holding, 2014).
1
Corresponding author
ISES Solar World Congress 2017 IEA SHC International Conference on
Solar Heating and Cooling for Buildings and Industry
© 2017. The Authors. Published by International Solar Energy Society
Selection and/or peer review under responsibility of Scientific Committee
doi:10.18086/swc.2017.12.02 Available at http://proceedings.ises.org
Urbanized dense cities lead to higher local ambient temperatures. As a result of this, the use of air-conditioning (AC)
units for cooling has immensely increased in Egypt. Conventional AC units represent the major energy consumption
of the residential energy demand (Xing Lu et al., 2016, Attia et al., 2012). On the other hand, in winter electric water
heating accounts for large shares of electricity demand, even in warm-climate countries. Nowadays, cooling in
residential buildings in Egypt is provided by not very efficient split units, which number grows very rapidly (Attia
et al. 2012). This leads to frequent electricity cut-offs in summer (Elharidy et al., 2013). Integration of renewable
energies to the space cooling and heating in residential buildings could be an environment-friendly and sustainable
solution.
Within the research project NightCool, funded by the German Federal Ministry of Education and Research (BMBF),
a concept for a low-cost system for heating and cooling applications was developed and simulated in detail.
The developed system consists of uncovered solar collectors for the energy production and an activated ceiling for
the energy distribution. Fig. 2 shows the principles of the energy supply system for direct cooling (left) and direct
heating (right). The space cooling is achieved at night by circulating the heat transfer fluid in the collectors (radiative
cooling) while the space heating is provided during the day by converting the solar energy into useful heat. Since
these collectors are not expensive, such a heating and cooling system results to be low-cost. The advantages of such
a simple system lie in simple installation and low energy costs (Eicker and Dalibard, 2011), which is very important
for solar thermal systems in order to achieve a higher market penetration (IEA SHC Task 54).
Fig. 2: Energy supply system that provides space cooling in summer (left) and space heating in winter (right)
In order to investigate the potential and limits of such a system, a mobile HIL test bench has been designed and
constructed. The present paper aims to show the advantages of using such a HIL environment show its limitations
and give some insights for further improvements.
2. Motivation to build a mobile HIL test bench
2.1. Motivation to build a mobile HIL test bench
As before mentioned, the project NightCool aimed to develop a low-cost system for heating and cooling applications
for Egyptian climate conditions. The estimation of the achievable return temperatures as well as the cooling power
by using solar collectors for radiative cooling applications needs adequate physical collector models.
ISO 9806:2017 specifies test methods for the thermal performance characterization of fluid heating collectors for
steady-state and quasi-dynamic conditions (ISO 9806, 2017). Based on this test method parameters for the
parameterization of collector models within the simulation environment TRNSYS such as Type 203 (PVT collectors)
(Bertram et al., 2011) or Type 1289 (flat plat collectors) can be determined. The deviation between measured
collector power output on a test stand and simulated power can vary between night and daytime (Cremers et al.,
2015). Especially for night time radiative cooling, the collector parameters determined according to ISO 9806:2017
are not sufficient enough to develop control strategies only by using a simulation model.
The motivation to build the HIL test bench in the NightCool project can be summarized as follows:
R. Braun / SWC 2017 / SHC 2017 / ISES Conference Proceedings (2017)
The thermal performance of solar collector at night cannot be modelled accurately with existing available
models so that their performance needs to be measured and not simulated.
Test new market available solar thermal collectors (which thermal performance is not specified by the
producer)
Test the integration of such collector into different systems and for different buildings construction (light or
heavy) and achieve a realistic estimation of the dynamics of the system, scalable and adaptable to different
kind of loads etc.
Dimension the system components and optimize the control before it can be installed on a bigger scale
Following table summarizes the main functionalities of the mobile HIL test bench and the benefit by setting up a
small scale test environment.
Tab. 1: Main functionalities of the mobile HIL test bench and the need and benefit
Functionality
Need and benefit
Conduct collector performance tests under
real conditions and conduct tests of solar
collectors at night time
Various solar collectors of different constructions from different
producers (basically swimming pool absorbers are recommended)
can be tested and a collector with a highest thermal potential and
best integration suitability (easily connected hydraulic connections,
appropriate mechanical properties, etc.) can be defined
For the cooling application, it is essential to know also the cooling
potential of different solar collectors. This information is missing in
technical data sheets, it can be obtained experimentally.
Analysis of the dynamic behaviour of
system components
It is important to understand the behaviour of the solar collector and
the building to define optimal control algorithms.
Development and test of control
algorithms for heating and cooling systems
depending on the defined system
The control algorithm of a system can be easily implemented in a
simulation environment such as TRNSYS either for cooling or
heating application. An optimal set of parameters such as the set
point temperatures to turn on or of the system.
Optimize building construction elements
so that they are appropriate for the
suggested cooling/heating system
By changing building parameters in the building model on the
simulation environment an optimal distribution system can be
defined (activated heating and cooling ceiling, floor heating or
others)
Estimation of achievable thermal comfort
e.g. temperature and relative humidity and
analysis of the activation capability of
building mass to act as energy storage
through different distribution systems e.g.
activated ceilings
Direct feedback from the simulation model helps analyse comfort
parameters and gives insight into the architectural concept of active
and passive measures (active and passive building design).
3. Mobile HiL test bench
3.1. Working principle and construction
The mobile HIL test bench has been designed and constructed within a research project aiming to develop a low-cost
space heating and cooling system for Egyptian climate conditions. The working principle of the HIL test bench
(Figure 3) is based on hardware-in-the-loop (HIL) simulation, a technique that is used in the development and test of
real-time embedded systems. The mobile HIL-Box consists of an uncovered solar collector (hardware component)
and a building simulation model (software component). It enables to conduct real-time measurements and simulations
to calculate at each time step the dynamic change of the system parameters such as room temperature and ceiling
temperature, as well as the cooling or heating power. The solar collector is replaceable, so that different solar
collectors can be tested. The building and the distribution system are defined in the simulation environment TRNSYS
(www.trnsys.com). Thus, an optimal solar system combination, solar collector (collector-type, -size, etc.) and
R. Braun / SWC 2017 / SHC 2017 / ISES Conference Proceedings (2017)
building properties (construction, size, materials, etc.) can be chosen. In other words, the HIL test bench enables to
optimize the building and the system at the early planning stage.
The main weather data (ambient temperature Ta, relative humidity RH, horizontal global irradiance Ghor, net long-
wave radiation GL and wind velocity w) and system parameters (inlet and outlet temperature Tin and Tout, flow rate
) are measured and acquired by several ethernet input modules connected with the software LabVIEW. The
measured data are given as inputs to the TRNSYS building model which calculates the building behavior and the
system response, such as room temperature Troom and the outlet temperature of the cooling ceiling Tcc. In the hydraulic
system the simulated Tcc is the same as the inlet collector temperature Tin. It is read in LabVIEW and transmitted as
set-point temperature via an analog output module to the temperature control unit (TCU). The TCU regulates then
the fluid inlet temperature of the solar collector, i.e it sets the inlet temperature equal to the Tcc Based on the
temperature difference (Tin Tout) and the fluid flow rate the cooling or heating power of the solar collector can be
calculated.
𝑄 = ṁ𝑐𝑝(𝑇𝑜𝑢𝑡 − 𝑇𝑖𝑛) (eq. 1)
where cp is the fluid heat capacity.
In the next step, the collector response and the weather data are measured and the procedure is repeated (see Figure
3).
Fig. 3: Working principle of the HIL test bench
The measuring box is shown in Figure 4 and its main components are listed in Table 2.
Tab. 2: List of the main components of the HIL test bench
Number
Manufacturer
1
AQSOL
2
Lauda
3
Delta Ohm
4
Delta Ohm
5
Thies Clima
6
Delta Ohm
7
Solar
8
Omega
9
-
10
Oventrop
11
Oventrop
12
SIKA
13
-
14
-
15
Turtle24
16
Consists of many components
R. Braun / SWC 2017 / SHC 2017 / ISES Conference Proceedings (2017)
Fig. 4: HIL test bench: a) general view closed, b) general view open, c) and d) weather station, e) hydraulic system, f) electric control
box
The simplified hydraulic scheme of the HIL test bench is shown in Figure 5. The solar absorber is connected to the
temperature control unit Lauda and the thermal fluid, forced by the pump, circulates through the absorber. The flow
rate is regulated by a valve with motor. The valve can be partly closed to reduce the flow rate. When the valve is
closed completely, there is no flow through the absorber.
Absorber Lauda
M
Fig. 5: Simplified hydraulic scheme of the HIL test bench (Lauda is the temperature control unit)
R. Braun / SWC 2017 / SHC 2017 / ISES Conference Proceedings (2017)
3.2. Data communication
The coupling between LabVIEW and TRNSYS requires a data communication between two softwares, which is
achieved by the means of ASCII files (text files read and written by both programmes). The different steps of this
communication has been programmed in LabVIEW and are shown in Figure 6.
Fig. 6: Data communication steps between Labview and TRNSYS for the HiL configuration
In the first step, the parameters which remain constant during the whole HIL test have to be entered by the user in
the LabVIEW graphical interface in order to define the system size as well as the main control parameters. In addition
the path locations of the necessary different files have to be defined.
In the second step, the measurement data are acquired in LabVIEW via the I/O modules and written in a ASCII file
to be read in TRNSYS. The data required by TRNSYS are listed in Table 3.
Tab. 3: Data transferred from LabVIEW to TRNSYS
Variable
Name
Unit
Ambient air temperature
Tamb
°C
Ambient air relative humidity
RH
%
Horizontal solar irradiance
Gh
W/m²
Effective sky temperature
Tsky
°C
Collector outlet fluid temperature
TcolOut
°C
Collector mass flow rate
mdotCol
kg/h
Collector aperture area
Acol
Specific heat of the collector fluid
cp
kJ/kgK
Density of the collector fluid
rho
kg/m³
Pipe diameter
dpipe
m
Pipe length
Lpipe
m
Building orientation
TURN
°
Then the TRNSYS program is run and the LabVIEW program stops until the simulation is finished. At the end of
the simulation, the main results are written by TRNSYS in a text file, read by LabVIEW and shown for visualization
(see Figure 7).
Enter constant
parameters in
Labview
Data acquisition of the
measurement data Write measurement data on
the TRNSYS input file
Launch
TRNSYS
simulation
Read TRNSYS
simulation results and
plot in Labview
Send control
signals
Timed loop (each 30 seconds)
R. Braun / SWC 2017 / SHC 2017 / ISES Conference Proceedings (2017)
Fig. 7: Screenshot of the HiL visualization in Labview (grey: measurement data, red: simulated data)
The data that are passed from TRNSYS to LabVIEW are listed in Table 4.
Tab. 4: Data communicated from TRNSYS to LabVIEW
Variable
Name
Unit
Outlet fluid temperature of the building heating/cooling distribution system
TdistOut
°C
Collector inlet temperature (after pipe)
TcolIn
°C
Building room temperature
Troom
°C
Control signal of the pump
CTRLpump
[0/1]
Heating/cooling power transferred to the building (+/-)
Qdist
W
Relative humidity of room air
RHroom
%
Infiltration gains
Qinf
W
Ventilation gains
Qvent
W
Radiative internal gains
QgainRad
W
Convective internal gains
QgainConv
W
Total solar radiation absorbed at all inside surfaces of zone
Qtsabs
W
Control signal heating
CTRLheat
[0/1]
Control signal cooling
CTRLcool
[0/1]
Control signal collector
CTRLcol
[0/1]
Control signal season
CTRLseason
[0/1]
Control signal winter
CTRLwinter
[0/1]
Control signal summer
CTRLsummer
[0/1]
Depending on the simulation results, the appropriate control signals of the inlet temperature to the solar collector and
the flow rates are sent via the I/O modules.
4. Example of measurement results
In this section, some results obtained in cooling mode with the developed HIL test bench are shown exemplarily.
The test bench has been operated for commissioning tests during one week between the 12th and the 19th of June
2017 for a typical Egyptian building and under the climate conditions of Stuttgart.
R. Braun / SWC 2017 / SHC 2017 / ISES Conference Proceedings (2017)
4.1. Constant parameters
The main constant parameters assumed for the test of the measurement box are summarized in Table 5.
Tab. 5: Main constant parameters
Parameters
Value
Unit
Collector area
70
Fluid density
1043
kg/m³
Fluid specific heat
3.675
kJ/kgK
Cooling set point
22
°C
Activated ceiling area
114
Initial building temperature
23.5
°C
4.2. Weather data
Figure 8 shows the main measured weather data during the considered period: the ambient temperature Tamb, the sky
temperature Tsky which is calculated with the help of the downward longwave radiation measured with the
pyrgeometer and the global irradiance on the horizontal plane Gh.
Fig. 8: Main weather data during the measurement period
4.3. Collector operation
Figure 9 shows, in addition to the ambient and sky temperatures, the main collector measured values: the inlet and
outlet temperatures Tin and Tout as well as the volumetric flow rate Vdot. The collector is operated in cooling mode,
i.e. at night according to a defined control strategy.
0
200
400
600
800
1000
1200
1400
0
5
10
15
20
25
30
35
40
12.06
12.06
13.06
13.06
13.06
13.06
13.06
14.06
14.06
14.06
14.06
14.06
15.06
15.06
15.06
15.06
15.06
16.06
16.06
16.06
16.06
16.06
17.06
17.06
17.06
17.06
17.06
18.06
18.06
18.06
18.06
19.06
19.06
19.06
Irradiance [W/m²]
Temperature [°C]
Main weather data
Tamb Tsky Gh
R. Braun / SWC 2017 / SHC 2017 / ISES Conference Proceedings (2017)
Fig. 9: Collector operation during the measurement period
4.4. Building behavior
Figure 10 shows the simulated building temperature Troom, the collector specific power QdotColSp transferred to the
building, as well as the total building specific gains QdotGains. The collector specific power is based on the collector
area (70 m²) whereas the building specific gains are based on the apartment floor area (115 m²). QdotColSp is defined
positive when cooling is provided to the building. QdotGains includes the internal gains, the solar gains, as well as the
ventilation and infiltration gains.
It can be seen that the building temperature Troom increases suddenly when the collector pump is switched ON at the
beginning of the night. This is due to the still hot fluid which is in the pipes and the collector and is pumped to the
building causing a temperature increase in the room. This can be easily solved by appropriate changes on the control
parameters.
Fig. 10: Main building results during the measurement period
In order to see the influence of the investigated system on the building temperature, a reference system (i.e. without
collectors) has been simulated. Figure 11 shows the room temperatures of the reference system and the night cooling
system for the three first nights of the considered measurement period. Due to the control problem mentioned earlier,
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0
10
20
30
40
50
60
70
12.06
12.06
13.06
13.06
13.06
13.06
13.06
14.06
14.06
14.06
14.06
14.06
15.06
15.06
15.06
15.06
15.06
16.06
16.06
16.06
16.06
16.06
17.06
17.06
17.06
17.06
17.06
18.06
18.06
18.06
18.06
19.06
19.06
19.06
Volumetric flow rate [l/s]
Temperature [°C]
Collector operation
Tamb Tsky Tin Tout Vdot
0
20
40
60
80
100
120
140
160
20
21
22
23
24
25
26
12.06
12.06
13.06
13.06
13.06
13.06
13.06
14.06
14.06
14.06
14.06
14.06
15.06
15.06
15.06
15.06
15.06
16.06
16.06
16.06
16.06
16.06
17.06
17.06
17.06
17.06
17.06
18.06
18.06
18.06
18.06
19.06
19.06
19.06
Specific power [W/m²]
Temperature [°C]
Building thermal power
Troom QdotColSp QdotGains
R. Braun / SWC 2017 / SHC 2017 / ISES Conference Proceedings (2017)
the room temperature of the radiative cooling system is higher at the beginning of the night (i.e. the building is
actually heated up) than the reference system. When the cooling power of the collector is positive (i.e. the building
is cooled down), the room temperature is lower than the reference system. The pump is stopped when this temperature
reaches 22°C.
Due to the chosen distribution system (thermally activated ceiling), both temperatures merge together as soon as the
collectors are not operated. Indeed, the activated ceiling of the TRNSYS building model assumes a unique thermal
coupling to the building air node. Therefore, the cooling provided by the collectors cannot be transferred to the
building thermal mass, causing a quick drop in the room temperature which has no effect on the room temperature
during day time. A better option would be in this case to connect the collector loop to an activated concrete core so
that the building thermal mass can be cooled down during the night and therefore providing additional thermal
comfort during the day.
Fig. 11: Comparison of the room temperatures with the night cooling system (red line) and without (grey dashed-line)
4.5. Summarized results
Table 6 shows the main summarized measurement results over the considered measurement period. These values
have been averaged or integrated only during the collector operation, i.e. when the collector pump was running (see
Figure 9).
Table 6: Summarized main measurement results over the considered period
Parameter
Value
Unit
Collector mean specific cooling power
75.9
W/m²
Mean sky temperature
9.3
°C
Mean ambient temperature
20.3
°C
Mean wind velocity
0.3
m/s
Mean downward longwave radiation
363.2
W/m²
Total cooling energy (one collector)
8,9
kWh
5. Conclusions and outlook
The present paper presents a mobile Hardware in the Loop test bench that allows to test solar assisted heating and
cooling systems based on low cost uncovered solar collector for the Egyptian climate. This test bench can be used
for collector testing and for system testing in a hardware in the loop configuration. The measurement results show
that a 70 m² collector could provide an average of 76 W cooling power per square meter and would be suitable for
the cooling of a 120 m² apartment. With the developed test bench, many kind of collector integrations can be tested
for different building constructions and system definitions. Also the control algorithm of the system can be tested
and optimized before the implementation in real systems.
21
21.5
22
22.5
23
23.5
24
24.5
25
12.06
12.06
12.06
12.06
12.06
13.06
13.06
13.06
13.06
13.06
13.06
13.06
13.06
13.06
13.06
13.06
13.06
13.06
14.06
14.06
14.06
14.06
14.06
14.06
14.06
14.06
14.06
14.06
14.06
14.06
14.06
14.06
15.06
15.06
15.06
15.06
15.06
Temperature [°C]
Building temperature
Troom Troom Ref
R. Braun / SWC 2017 / SHC 2017 / ISES Conference Proceedings (2017)
The developed test bench will be transported to Egypt and further used for both collector and system testing at the
German University of Cairo (GUC). In particular the following improvements will be done by modifying the systems
in the TRNSYS model:
Activate the building thermal mass (Type 56) by changing from chilled ceiling to activated ceiling
Integrate a water store in the system for domestic hot water preparation
Add a water storage to store the cold at night and use it during the day
Modify the control so that the collector energy yield is increased
6. Acknowledgements
The project NightCool was supported by the German Federal Ministry of Education and Research (BMBF). Support
code: 01DH14021.
7. References
Attia, S., Evrard, A. Gratia, E., 2012. Development of benchmark models for the Egyptian residential buildings
sector. In: Applied Energy 94, pp. 270284.
Bertram E., Kirchner M., Rockendorf G.. “Solare Gebäudewärmeversorgung mit unverglasten photovoltaisch-
thermischen Kollektoren, Erdsonden und Wärmepumpen für 100% Deckungsanteil, Kurzbezeichnung: BiSolar-WP,
Hameln/Emmerthal, (2011) Final Report.
Cremers J., Eicker U., Palla N., Jobard X., Klotz F., and Mitina I.. PVT Integral Research Project. Multivalente PV
sowie thermische Kollektoren zur Kälte-, Wärme- und Stromerzeugung und Szenarien für die Gebäudeintegration.
Project duration 2012 2015. (2015) Final Report.
Egyptian Electricity Holding Company. Annual Report 2013/2014. English. Ministry of Electricity and Renewable
Energy - Arab Republic of Egypt.
Eicker Ursula and Dalibard Antoine. Photovoltaicthermal collectors for night radiative cooling of buildings. In:
Solar Energy Volume 85, Issue 7, July 2011, pp. 1322-1335.
Elharidy et al. Facing the Growing Problem of the Electric Power Consumption in Egyptian Residential Building
Using Building Performance Simulation Program. In: Building Simulation - Towards Sustainable & Green Built
Environment. Egyptian Group for Energy in Buildings and Environmental Design Research. Cairo, June 2013.
IEA SHC Task 54. Price Reduction of Solar Thermal Systems. Project duration October 2015-October 2018. Solar
Heating & Cooling Programme International Energy Agency.
ISO 9806:2017, 2017. Solar energy -- Solar thermal collectors -- Test methods. International Organization for
Standardization (ISO).
United Nations, Department of Economic and Social Affairs, Population Division (2017). World Population
Prospects: The 2017 Revision, Key Findings and Advance Tables. Working Paper No. ESA/P/WP/248.
Xing Lu et al. Cooling potential and applications prospects of passive radiative cooling in buildings: The current
state-of-the-art. In: Renewable and Sustainable Energy Reviews 65 (2016), pp. 10791097.
R. Braun / SWC 2017 / SHC 2017 / ISES Conference Proceedings (2017)
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
The aim of this study is to develop representative simulation building energy data sets and benchmark models for the Egyptian residential sector. This study reports the results of a recent field survey for residential apartment buildings in Egypt. Two building performance simulation models are created reflecting the average energy consumption characteristics of air-conditioned residential apartments in Alexandria, Cairo and Asyut. Aiming for future evaluation of the cost and energy affects of the new Egyptian energy standard this study established two detailed models describing the energy use profiles for air-conditioners, lighting, domestic hot water and appliances in respect to buildings layout and construction. Using EnergyPlus simulation tool the collected surveyed data was used as input for two building simulation models. The simulation models were verified against the apartment characteristic found in the survey. This paper presents details of the building models including the energy use patterns and profiles created for this study.
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Bertram E., Kirchner M., Rockendorf G.. "Solare Gebäudewärmeversorgung mit unverglasten photovoltaischthermischen Kollektoren, Erdsonden und Wärmepumpen für 100% Deckungsanteil, Kurzbezeichnung: BiSolar-WP, Hameln/Emmerthal, (2011) Final Report.
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Facing the Growing Problem of the Electric Power Consumption in Egyptian Residential Building Using Building Performance Simulation Program
  • Elharidy
Elharidy et al. Facing the Growing Problem of the Electric Power Consumption in Egyptian Residential Building Using Building Performance Simulation Program. In: Building Simulation -Towards Sustainable & Green Built Environment. Egyptian Group for Energy in Buildings and Environmental Design Research. Cairo, June 2013.
Solar energy-Solar thermal collectors-Test methods. International Organization for Standardization (ISO)
ISO 9806:2017, 2017. Solar energy-Solar thermal collectors-Test methods. International Organization for Standardization (ISO).
IEA SHC Task 54. Price Reduction of Solar Thermal Systems
IEA SHC Task 54. Price Reduction of Solar Thermal Systems. Project duration October 2015-October 2018. Solar Heating & Cooling Programme International Energy Agency.
Solar energy --Solar thermal collectors --Test methods
ISO 9806:2017, 2017. Solar energy --Solar thermal collectors --Test methods. International Organization for Standardization (ISO).