ArticlePDF Available

Applicability Study on a Hybrid Renewable Energy System for Net-Zero Energy House in Shanghai

Authors:

Abstract and Figures

Governments around the world are establishing technological routes and tactics for low/zero-energy buildings to reduce emissions and energy use. This paper describes a hybrid renewable energy system developed for a net-zero energy low-rise residential building located in Shanghai, China. This hybrid renewable energy system consists of a water-based photovoltaic/thermal (PVT) collector and a ground water-source heat pump (GWSHP). The hybrid system is designed to produce heating, cooling and electricity during both winter and summer by using solar energy and ground surface water energy respectively. Firstly, field tests on the PVT collector and GWSHP were carried out to obtain their thermal performance, and then analytical models for the PVT collector and performance curve of the GWSHP were developed and validated by the experimental data. In addition, the balance between annual energy production and consumption was estimated to evaluate the applicability of this system for the on-grid net-zero energy residential building in Shanghai. It is shown that the detached house with the PVT-GWSHP system can provide 109.3% of total requirements for heating, cooling and electricity, and has potentials to realize the net-zero energy target.
Content may be subject to copyright.
1876-6102 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the organizing committee of CUE 2015
doi: 10.1016/j.egypro.2016.06.108
Energy Procedia 88 ( 2016 ) 768 774
ScienceDirect
CUE2015-Applied Energy Symposium and Summit 2015: Low carbon cities and urban
energy systems
Applicability Study on a Hybrid Renewable Energy System
for Net-Zero Energy House in Shanghai
Shihao Zhanga, Zhi Zhuangb,
*
, Yidong Hua, Baoshun Yanga, Hongwei Tanb
aCollege of Mechanical and Energy Engineering, Tongji University, Shanghai 201804, China
bCollege of Architecture of Urban Planning,Green Building and New-Energy Insitute, Tongji University, Shanghai 200092, China
Abstract
Governments around the world are establishing technological routes and tactics for low/zero-energy buildings to reduce
emissions and energy use. This paper describes a hybrid renewable energy system developed for a net-zero energy low-
rise residential building located in Shanghai, China. This hybrid renewable energy system consists of a water-based
photovoltaic/thermal (PVT) collector and a ground water-source heat pump (GWSHP). The hybrid system is designed
to produce heating, cooling and electricity during both winter and summer by using solar energy and ground surface
water energy respectively. Firstly, field tests on the PVT collector and GWSHP were carried out to obtain their thermal
performance, and then analytical models for the PVT collector and performance curve of the GWSHP were developed
and validated by the experimental data. In addition, the balance between annual energy production and consumption
was estimated to evaluate the applicability of this system for the on-grid net-zero energy residential building in
Shanghai. It is shown that the detached house with the PVT-GWSHP system can provide 109.3% of total requirements
for heating, cooling and electricity, and has potentials to realize the net-zero energy target.
© 2015 The Authors. Published by Elsevier Ltd.
Selection and/or peer-review under responsibility of CUE
Keywords: Net-zero energy building; Photovoltaic/thermal collector; Ground water-source heat pump; Building energy simulation.
1. Introduction
The utilization of renewable energy for low/zero-energy buildings mainly includes solar photovoltaic
technology, solar thermal technology, ground source heat pump and etc. [1]. Photovoltaic/thermal (PVT)
* Corresponding author. Tel.: +086-21-65980778; fax: +086-21-65981002
E-mail address: zhuangzhi@tongji.edu.cn
Available online at www.sciencedirect.com
© 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the organizing committee of CUE 2015
Shihao Zhang et al. / Energy Procedia 88 ( 2016 ) 768 – 774 769
collector is an efficient holistic solar energy solution that simultaneously converts solar energy into
electricity and heat [2]. A trend of comprehensive utilization of renewable energy and low-level thermal
energy is to integrate the PV system with the heating, ventilation, and air conditioning (HVAC) system. Up
to date, various studies have been undertaken on solar heating system [3], solar-absorption refrigerating
system, solar assisted ground source heat pump heating system [4], etc. However, the promotion and
application of these hybrid renewable energy systems, sustainable operation has become the major
constraints. The energy supply of solar photovoltaic/thermal system is unstable due to the influence of
weather variations, and the performance of ground source heat pump is limited by site condition and source
capacity. Therefore, the maximum utilization of those renewable system has not been well studied.
This study developed and implemented an innovative HVAC system incorporating a hybrid renewable
energy system, sufficiently utilizing solar energy to generate electricity as well as to pre-heat the water into
the GWSHP. The heated water then improves the secondary heating efficiency of GWSHP in winter and
reduces the domestic hot water heating energy through the year. The objective of this study is to prove the
applicability of this hybrid renewable energy system particularly for zero-energy house in Shanghai, the
hot-summer and cold-winter zone of China with insufficient solar irradiation.
2. System introduction
2.1. Building and system layout
The experimental house as shown in Figure 1 locates in Shanghai, China. The specification is shown in
Table 1. The PVT collectors are implemented on the roof within the buildings footprint. The electricity
generated by the PVT can access city power grid after converted into alternating current by the inverter.
The PVT collector heats water coming from the water storage tank and thereby provides heating to the heat
storage water tank connected with the ground heat exchanger as the hot water source in winter. Ground
surface water piping system is also implemented as an alternative water source to the heat exchanger, which
is illustrated in Figure 2.
Figure 1 Zero-energy residential house
770 Shihao Zhang et al. / Energy Procedia 88 ( 2016 ) 768 – 774
Table 1. Residential building specification
Items
Value
Floor to ceiling height
3.05 m
HVAC system
Fan coil; Temperature & humidity independently controlled
Ventilation rate
30 m3/h person
Hot water
200 L/day
Building envelope
Exterior walls
0.1 W/(m2.K)
Interior walls
0.4 W/(m2.K)
Windows
0.8 W/(m2.K); Solar heat gain coefficient (SHGC) 0.5
Glass door
0.8 W/(m2.K); Solar heat gain coefficient (SHGC) 0.5
Roof
0.12 W/(m2.K)
Shading coefficient (SC)
0.73
Figure 2 Schematic of system configurations: GWSHP and PVT
2.2. Operating strategies
In winter, since the daily solar radiation is unsteady, when the temperature of the heat storage water tank
goes below the lower limit, the ground heat exchanger will switch the valves to the ground surface water
piping system as water source. The temperature of the hot water storage tank and water storage tank would
be kept in a proper range, to meet both the demand of the heat pump and PVT module.
During the cooling season, the valves are switched to ground surface water piping system, providing
cooling water for the heat exchanger and the return water goes to the water storage tank. Domestic hot
water can be made by the heat pump when valves are switched to the hot water storage tank.
3. System test and modelling
Shihao Zhang et al. / Energy Procedia 88 ( 2016 ) 768 – 774 771
3.1. Field test parameters
Field test had been conducted through the year. Parameters including inlet/outlet temperature, flow rate,
electricity production/consumption, solar radiation intensity, COP of GWSHP and generating capacity and
efficiency of PVT were recorded.
3.2. PVT analytical model
By synthesizing and test data analysis, the soar irradiation intensity, PVT inlet water temperature and
ambient temperature appear as three specific parameters of PVT heat-collecting efficiency. Then
mathematical model can be established by regressing fitting, with difference less than 15%. Similarly, the
PV panel temperature and irradiation intensity are specific parameters of PVT generating efficiency, but
those two parameters are not mutual independent, a large portion of solar irritation will convert to heat, thus
raise the temperature of PV panel. A practical method is discovered that divides the date with specific
temperature range, the generating efficiency and thermal collecting efficiency of the PVT can be obtained
with a good consistency (as shown in Figure 3 and 4) by regression analysis which has linear performance
with incident solar irradiation. The summary of the PVT mathematical model is given in Table 2.
Figure 3 PVT generating efficiency
Figure 4 PVT thermal collecting efficiency
772 Shihao Zhang et al. / Energy Procedia 88 ( 2016 ) 768 – 774
Table 2 Summary of the PVT mathematical model
Conditions
5~25°C, 0~1000W/m²
25~35°C, 0~500W/m²
25~35°C, 500~1000W/m²
35~60°C, 0~1000W/m²
5~60°C, 0~1000W/m²
4. Results and discussion
4.1.
Annual energy consumption/production
The annual energy consumption of the studied system was 3658.7kWh, and the overall energy
consumption intensity was 65.3kWh/m2. The breakdown demonstrated that HVAC annual consumption
was 2076.0kWh, lighting was 648.7Wh, and the rest were other equipment consisting of 934.1kWh.
The installed capacity of PVT collector is 26.2m2, and the volume of the hot water storage tank is 1.4m3.
The annual energy production can be calculated by the PVT mathematical model using the Solar and Wind
Energy Resource Assessment (SWERA) data of Shanghai. Figure 5 shows the monthly power generation
and consumption of the building. The annual on-site power generation intensity was 152.6kWh/ m2.
The annual energy consumption and production for the whole year is illustrated in Figure 6. During the
heating period, the total electricity generation is 1222.7 kWh, thermal energy collection is 2122.0 kWh,
while the system energy consumption is 1476.7 kWh. While during the cooling period, the total electricity
generation is 1608.5 kWh, thermal energy collection is 4517.1 kWh, while the system energy consumption
is 1538.0 kWh. Besides, the low-level thermal energy is utilized through the year. During the cooling and
transition seasons, the PVT heated water is not consumed by the HVAC system, however this accordingly
contributes to reduce the energy consumption of domestic hot water supply.
Figure 5 Annual power generation/consumption
Shihao Zhang et al. / Energy Procedia 88 ( 2016 ) 768 – 774 773
Figure 8 Annual energy consumption and production
5. Conclusions
This paper introduced an innovative hybrid PVT-GWSHP renewable energy system for a net-zero
energy house, which is designed to produce heating, cooling and electricity during both winter and summer
by using solar energy and ground surface water energy respectively. The applicability of the hybrid PVT-
GWSHP system in detached house located in hot summer and cold winter city Shanghai was evaluated by
both field test and modelling analysis. The annual energy consumption of the studied case is 3658.7kWh,
less than the annual on-site energy generation 4000.1kWh, and the system has been proved to be applicable
on this on-grid zero-energy house, and hence has potential for low/zero-energy low-rise residential
buildings in Shanghai. The utilization of the test and simulation data for system optimization, as well as the
economic analysis and environment impact assessment for the system will be studied in near future.
Acknowledgements
The work was supported by the Fundamental Research Funds for the Central Universities and a grant
from the Science & Technology Planning Project by Ministry of Housing and Urban-Rural Development,
(No. 2014-K1-036). Thanks to Lei Y. for his technical insights and advice.
References
[1] Tan H. The development and applicability of renewable energy for buildings. Building Science 2015;8:34-42
[2] Tiwari G N, Mishra R K, Solanki S C. Photovoltaic modules and their applications: A review on thermal modelling. Applied
Energy 2011; 88(7):2287-2304.
[3] Ortiz M, Barsun H, He H, et al. Modeling of a solar-assisted HVAC system with thermal storage. Energy and Buildings 2010;
42(4):500-509.
[4] Ozgener O, Hepbasli A. Experimental Performance Analysis Of A Solar Assisted Ground-Source Heat Pump Greenhouse
Heating System. Energy and Buildings 2005;37(1):101-110.
774 Shihao Zhang et al. / Energy Procedia 88 ( 2016 ) 768 – 774
Nomenclature
¨
pv Generating efficiency of PVT
¨
th thermal collecting efficiency of PVT
G Irradiation intensity
ti Inlet water temperature
ta Ambient temperature
Biography
Dr. Zhi Zhuang is an Assistant Professor from the College of Architecture of Urban
Planning in Tongji University of China. His research interest is building energy
efficiency, renewable energy application and green building design.
... Based on simulation results, it was found that these renewable energy sources would be a feasible solution for zero energy buildings. A paper [3] demonstrates a hybrid renewable energy system developed for a net-zero energy low rise residential building located in Shanghai, China that hybrid renewable energy system consists of a water-based photovoltaic/thermal (PVT) collector and a ground water-source heat pump (GWSHP) which was designed to produce heating, cooling and electricity during both winter and summer by using solar energy and ground surface water energy respectively. The feasibility of that hybrid system for a detached house located in hot summer and cold winter city Shanghai was evaluated by both field test and modeling analysis. ...
Conference Paper
Full-text available
In this paper, a hybrid power system is designed for a house in St. John's. House located in Newfoundland is designed using the Energy 3D software and the annual energy (kWh) demand for the house is determined. The hybrid power system to meet this energy demand is designed and simulated using both Homer (Hybrid Optimization of Multiple Electric Renewables) Pro software and iHOGA (improved hybrid optimization genetic algorithm) software. Analysis reveals that for Homer Pro software, 95.8% (52,566kWh/yr) of the total annual energy is produced by the wind turbine and 4.2% (2,308kWh/yr) is produced by the solar cells. For the iHOGA software, 85.7% (8,188.6kWh/yr) of the total annual energy is produced by the wind turbine and 14.3% (1,361.6kWh/yr) is produced by the solar cells. Further analysis indicates that it more economical to design the hybrid power system in iHOGA software. However, irrespective of the software used in the system design, the energy generated for the isolated system is more than the energy demand of the house thus leaving excess electricity that can be sold to the grid system.
... Also, in the case of excess power production, it can be sold to the main grid. In 2016, Zhang et al., [34] presented a hybrid-renewable energy system developed for a net-zero energy low-rise residential building. This hybrid renewable energy system consisted of a water-based photovoltaic/thermal (PVT) collector and a ground water-source heat pump. ...
Article
Full-text available
The main objective of the present research is to design a hybrid wind and solar energy-supply system for a rural residential building to meet its energy demands. The monthly averaged daily energy consumption for the dwelling was found to vary between 19 and 36 kWh. The system under consideration included some subsystems, namely: the hot-water service, the space-heating facility, and the power-utility system (wind electricity supply and storage system). The optimum design was obtained by carrying out a cost-benefit analysis for each of the subsystems. The hot-water system was designed to be based on solar flat-plate collectors, and a wind tree. The optimum hot-water facility is consisted of three flat-plate collectors, a storage heat exchanger with three coils, which are attached to flat-plate solar collectors, under-floor heating systems, and a wind tree power system. The large dimensions of the house were the limiting factor when investigating the feasibility of a solar-powered space-heating system. The existence of large windows made the space heating a very difficult and expensive task. The results show that the cost of the system is very expensive compared to the connection to the main grid. But on the other side, there will be a return investment value each year and the system will get all its costs after 14 years. Thus, if the average life of the system is 20 years old, the system will get profit after 14 years for six more years, in addition to the clean energy out from the system and the very beneficial positive effect on the environment.
... Buildings with two-way interaction with the local energy grids are the main characteristic of smart energy systems, paving the path for truly having net-zero buildings, that is, buildings with (almost) zero emissions. A CCHP solar-based building system consisting of a PVT and a heat pump with two-way interaction with electricity, heat, and cooling networks was introduced and investigated by Zhang et al. [17]. They obtained a balance between the produced annual electricity, heat, and cooling productions and use with 109% supply of the total building's energy requirement. ...
Article
This study introduced an innovative yet feasible and cost-effective solution to make a big step forward in the state-of-art of smart energy buildings and obtain a real meaning of net-zero energy building. In this study, the main cornerstones of the developed solution combined the following technologies: the use of novel trigeneration solar collectors without a battery, a very clever method of heat pump integration with minimal size and cost required, and two-way interaction of the building with local energy networks. Different system configurations based on the included components were suggested and analyzed for an apartment building in Denmark. A thorough techno-economic and environmental evaluation of the proposed solution and the most competent ones already proposed for the same application was carried out to rank the best configuration from various facets. A comparative parametric study was accomplished to examine and compare the variation of performance indicators with significant decision variables. In addition, the tri-objective optimization was implemented for each configuration to specify the best optimum condition from energy, economic, and environmental standpoints. According to the economic results, the configurations integrated with battery and regular heat pumps were not favorable due to the highest total cost and the payback period. Here, the proposed system, owing to its resilient energy trade possibility with the energy networks and the scaled-down heat pump, gave larger energy-saving and CO2 emission reduction rates of 16.6% and 21.6%, respectively. The multi-objective optimization showed that the capacities of the battery and the cold storage were the most effective parameters on the performance of the system.
... The use of these storage systems provides the possibility for 100% renewable power generation in remote areas [17]. In 2016, Zhang et al. [18] presented a hybrid-renewable energy system developed for a netzero energy low-rise residential building. This hybrid renewable energy system consisted of a water-based photovoltaic/thermal (PVT) collector and a ground water-source heat pump. ...
Conference Paper
Full-text available
The main objective of the present research isto design a hybrid wind and solar energy-supply system for a rural residential building to meet its energy demands. The monthly averaged daily energy consumption for the dwelling was found to vary between 19 and 36 kWh. The system under consideration included some subsystems, namely: the hot-water service, the space-heating facility, and the power-utility system (wind electricity supply and storage system). The optimum design was obtained by carrying out a cost-benefit analysis for each of the subsystems. The hot-water system was designed to be based on solar flat-plate collectors, and a wind tree. The optimum hot-water facility is consisted of three flat-plate collectors, a storage heat exchanger with three coils, which are attached to flat-plate solar collectors, under-floor heating systems, and a wind tree power system. The large dimensions of the house were the limiting factor when investigating the feasibility of a solar-powered space-heating system. The existence of large windows made the space heating a very difficult and expensive task. The results show that the cost of the system is very expensive compared to the connection to the main grid. But on the other side, there will be a return investment value each year and the system will get all its costs after 14 years. Thus, if the average life of the system is 20 years old, the system will get profit after 14 years for six more years, in addition to the clean energy out from the system and the very beneficial positive effect on the environment.
... The escalation of world's population has led to an increased demand of resources including water, electricity, and housing [1]. Consumption of fossil fuels has also increased in order to meet the human demands resulting in environmental degradation [2,3]. Scientists and researchers are putting [28]. ...
Article
Full-text available
Harnessing solar energy using photovoltaic cells seems a good alternative to fossil fuels as the power from sun intercepted by earth is about 1.8 × 1011 MW. However the heat trapped in photovoltaic cells during operation decreases the efficiency of the system. Recent advancements in nanotechnology have enabled scientists to enhance the efficiency of solar power generation by employing nanofluids and PCM based coolant in PV/T systems. This study comprehensively analyses the effective parameters of nanofluids and PCM that enhance the thermal, electrical and overall efficiency of the PV/T system. In this work nanofluid as a coolant and optical filter, nanofilm as optical filter, their merits and demerits were emphasised. This covers both experimental as well as numerical work performed by researchers in the field of hybrid PV/T systems with different nanofluids, various level of particle concentration, different geographical location and their end result in an elaborative sense. This review can become a good guide for the further researches to be made in the field of hybrid PV/T systems and can provide new directions to work in this field by working on the various designs in which nanofluid is used as coolant and optical filter.
Article
Full-text available
Net-zero energy buildings (NZEBs) were proposed as a viable solution for reducing building energy usage and contamination emission levels. To achieve the desired specific objective, the setups and abilities of the deployed RES in NZEBs should be carefully chosen. The goal of this project is to develop an optimized design approach for a zero-energy building that takes into account the building's usage of energy. The continuous expansion of international energy demand as a result of industrialization and growing populations is presently a major source of concern.
Presentation
Full-text available
The main objective of the present research is to design a hybrid wind and solar energy-supply system for a rural residential building to meet its energy demands. The monthly averaged daily energy consumption for the dwelling was found to vary between 19 and 36 kWh. The system under consideration included some subsystems, namely: the hot-water service, the space-heating facility, and the power-utility system (wind electricity supply and storage system). The optimum design was obtained by carrying out a cost-benefit analysis for each of the subsystems. The hot-water system was designed to be based on solar flat-plate collectors, and a wind tree. The optimum hot-water facility is consisted of three flat-plate collectors, a storage heat exchanger with three coils, which are attached to flat-plate solar collectors, under-floor heating systems, and a wind tree power system. The large dimensions of the house were the limiting factor when investigating the feasibility of a solar-powered space-heating system. The existence of large windows made the space heating a very difficult and expensive task. The results show that the cost of the system is very expensive compared to the connection to the main grid. But on the other side, there will be a return investment value each year and the system will get all its costs after 14 years. Thus, if the average life of the system is 20 years old, the system will get profit after 14 years for six more years, in addition to the clean energy out from the system and the very beneficial positive effect on the environment.
Article
Full-text available
In order to improve the heat transfer in enclosure structure of passive houses in cold area with complex climatic conditions, a three-dimensional model is established to investigate the time-by-case changes of outdoor temperature and solar irradiation based on the principle of integral change and the method of response coefficient and harmonious wave reaction. The variations of hourly cooling and heating loads with outdoor temperature and solar irradiation are analyzed. As simulated by cloud computing technology, the passive building energy consumption meets the requirements of passive building specifications. In the present research, super-thermal insulation external wall, enclosure structure of energy-conserving doors and windows, and high efficiency heat recovery system are employed to achieve a constant temperature without active mechanical heating and cooling, which suggests a strategic routine to remarkably decrease the total energy consumption and annual operation cost of passive building.
Article
Full-text available
At the background of urbanization in China, energy consumption of buildings has been ranked as the second largest sector among the industry, building and transportation. Consequently, the renewable energy adopted in buildings has been quickly developed since the Chinese policy, which shifts 60% of total photovoltaic applications to the building sector, was enhanced. This paper discusses suitability of renewable energy applied in buildings, including solar thermal energy (ST), photovoltaic (PV) and geothermal heat pump systems (GSHP), based on GIS database and operation data analysis. GIS-based tools are also developed for evaluating suitability of renewable energy applied in buildings.
Article
Ground-source heat pumps (GSHPs), also known as geothermal heat pumps (GHPs), are recognized to be outstanding heating, cooling and water heating systems, and have been used since 1998 in the Turkish market. Greenhouses also have important economical potential in Turkey’s agricultural sector. In addition to solar energy gain, greenhouses should be heated during nights and cold days. In order to establish optimum growth conditions in greenhouses, renewable energy sources should be utilized as much as possible. It is expected that effective use of heat pumps with a suitable technology in the modern greenhouses will play a leading role in Turkey in the foreseeable future.The main objective of the present study is to investigate to the performance characteristics of a solar assisted ground-source heat pump greenhouse heating system (SAGSHPGHS) with a 50 m vertical 1 × 1/4 in. nominal diameter U-bend ground heat exchanger using exergy analysis method. This system was designed and constructed in Solar Energy Institute of Ege University, Izmir, Turkey. The exergy transports between the components and the destructions in each of the components of the SAGSHPGHS are determined for the average measured parameters obtained from the experimental results. Exergetic efficiencies of the system components are determined in an attempt to assess their individual performances and the potential for improvements is also presented. The heating coefficient of performances of the ground-source heat pump unit and the overall system are obtained to be 2.64 and 2.38, respectively, while the exergetic efficiency of the overall system is found to be 67.7%.
Article
A numerical model of the solar-thermal-assisted heating, ventilation and air conditioning system in a 7000 m2 educational building, situated in a high-desert climate, is used to predict performance and optimize control parameters. Heating, cooling and shoulder seasons are considered in the study. It is found that the solar assist can account for over 90% of the total heating requirements if certain energy conservation strategies are adopted. The solar cooling assist can reduce the total external cooling energy requirement by between 33% and 43%, the latter result achieved, surprisingly, at lower solar array operating temperatures. In the shoulder season, it is possible to operate the building without any external contribution, by heating the building in the coldest hours of the day, and using any excess heat to produce chilled water, to be stored and used when required. Operation of the solar-assisted system within a much larger district energy system makes it possible to achieve maximum performance.
Article
Renewable energy (RE) resources have enormous potential and can meet the present world energy demand by using the locally available RE resources. One of the most promising RE technologies is photovoltaic (PV) technology. This paper presents a review of the available literature covering the various types of up and coming PV modules based on generation of solar cell and their applications in terms of electrical as well thermal outputs. The review covers detailed description and thermal model of PV and hybrid photovoltaic thermal (HPVT) systems, using water and air as the working fluid. Numerical model analysis and qualitative evaluation of thermal and electrical output in terms of an overall thermal energy and exergy has been carried out. Based on the thorough review, it is clear that PVT modules are very promising devices and there exists a lot of scope to further improve their performances particularly if integrated to roof top. Appropriate recommendations are made which will aid PVT systems to improve their overall thermal and electrical efficiency and reducing their cost, making them more competitive in the present market.