International Energy Agency Solar Heating Research Articles

Solar Energy in Urban Planning: Lesson Learned and Recommendations from Six Italian Case Studies

This paper presents the results of the analysis conducted on six case studies related to solar energy integration in urban and rural environments located on the Italian territory. The analysis has been carried out within the Subtask C—Case Studies and Action Research of the International Energy Agency Solar Heating and Cooling Program Task 51 “Solar Energy in Urban Planning”. Three different environments hosting active and passive solar energy systems (existing urban areas, new urban areas, and agricultural/rural areas) have been investigated to attain lessons learned and recommendations. Findings suggest that (a) it is important to consider solar energy from the early stages of the design process onwards to achieve satisfactory levels of integration; (b) a higher level of awareness regarding solar potential at the beginning of a project permits acting on its morphology, achieving the best solution in terms of active and passive solar gains; (c) when properly designed, photovoltaic systems can act as characterizing elements and as a distinctive architectural material that is able to valorize the aesthetic of the entire urban intervention; (d) further significant outcomes include the importance of supporting the decision strategies with quantitative and qualitative analyses, the institution of coordinating bodies to facilitate the discussion between stakeholders, and the need for deep renovation projects to fully impact existing buildings’ stock; (e) when large solar installations are planned at the ground level, a landscape design approach should be chosen, while the ecological impact should be reduced by carefully planning the adoption of alternative solutions (e.g., agrivoltaics) compatible with the existing land use.

Experimental analysis of thermal energy storage by phase change material system for cooling and heating applications

International Energy Agency Solar Heating & Cooling programme states the fact that space heating and cooling demand account for over 75% of the energy consumed in single and multi-family homes. By avoiding conventional methods for thermal storage, phase change materials (PCMs) provide heat storage and provide nearly constant temperature and at much higher energy storage densities. This technology can meet up to maximum of this demand depending on the region’s climate. Active and passive systems are used for this purpose. This study belongs to passive system, night ambient temperatures and solar energy for cooling and heating of buildings. PCMs could be stored with building substance used in floor to enhance their thermal storage capacity. Compare to other principles for thermal energy storage latent heat storage is competent because of small changes in temperature leads to storage density, promising technologies with low heat losses and attractive prices. This research is carried out to assess the performance of air based PCM storage system for cooling and heating of building. The execution of the concentrated on Phase change material storage system was noted maximum when melting point of Phase change material was 22.5°C in winter season and 28.8°C(∼29°C) during summer period. Summer, whereas 26.8°C was found during remaining part of the year. When the temperature goes below 26.8°C, cooling capacity of system is more as compare to heating capacity. Study also concludes that the effect of melting point of PCM has a great effect on cooling in summer period and its storage can be used in winter season.

Solar heating and cooling systems versus conventional systems assisted by photovoltaic: Application of a simplified LCA tool

Life Cycle Assessment (LCA) is an effective methodology to assess the energy and environmental impacts of energy systems during their life cycle, including manufacturing, operation and end-of-life.The aim of the paper is the application of a simplified LCA tool, developed in the framework of the International Energy Agency Solar Heating and Cooling Task 48, for comparing different typologies of solar assisted heating and cooling systems.In detail, solar thermal heating and cooling systems located in Palermo (southern Italy) and in Zurich (Switzerland) were compared with conventional systems assisted by grid connected and stand-alone photovoltaic plants.A validation of the tool was also carried out by comparing the obtained results with those of in-depth LCA studies.The results showed that the best system configuration in Palermo is the conventional system assisted by a grid-connected photovoltaic plant. Its impact on global energy requirement is about 83.7% and 74.5% of the corresponding impact of the solar thermal heating and cooling and the conventional system assisted by a stand-alone photovoltaic system, respectively.Different considerations can be made for Zurich, where the solar heating and cooling system performs better than the others; it is characterized by a global energy requirement that is 85.3% and 81.2% of the grid-connected and stand-alone photovoltaic assisted conventional systems, respectively. A similar trend is traceable for the global warming potential indicator.The validation of the LCA tool proved it to be reliable since deviations with a detailed LCA of the same system are contained below a 5% difference in all the comparable systems.

Preliminary survey on site-adaptation techniques for satellite-derived and reanalysis solar radiation datasets

At any site, the bankability of a projected solar power plant largely depends on the accuracy and general quality of the solar radiation data generated during the solar resource assessment phase. The term “site adaptation” has recently started to be used in the framework of solar energy projects to refer to the improvement that can be achieved in satellite-derived solar irradiance and model data when short-term local ground measurements are used to correct systematic errors and bias in the original dataset. This contribution presents a preliminary survey of different possible techniques that can improve long-term satellite-derived and model-derived solar radiation data through the use of short-term on-site ground measurements. The possible approaches that are reported here may be applied in different ways, depending on the origin and characteristics of the uncertainties in the modeled data. This work, which is the first step of a forthcoming in-depth assessment of methodologies for site adaptation, has been done within the framework of the International Energy Agency Solar Heating and Cooling Programme Task 46 “Solar Resource Assessment and Forecasting”.

Analysis of Photovoltaic Applications in Zero Energy Building Cases of IEA SHC/EBC Task 40/Annex 52

A Net Zero Energy Building (NZEB) considerably reduces the building energy load through high efficiency equipment and passive elements such as building orientation, high insulation, natural daylighting, and ventilation in order to achieve zero energy balance with on-site energy production from renewable energy systems applied to the building. For a Zero Energy Building (ZEB), the heating energy demand can be significantly reduced with high insulation and air tightness, while the cooling energy demand can be curtailed by applying shading device, cross ventilation, etc. As such, the electrical energy demand for a ZEB is relatively higher than its heat energy demand. Therefore, the application of a Renewable Energy System (RES) to produce electricity is necessary for a ZEB. In particular, Building Integrated Photovoltaic (BIPV) systems that generate electricity can play an important role for achieving zero energy balance in buildings; BIPVs are multi-functional and there are many ways to apply them into buildings. This study comprehensively analyzes photovoltaic (PV) applications in ZEB cases through the International Energy Agency Solar Heating and Cooling Programme (IEA SHC)/Energy in Buildings and Communities Programme (EBC) Task 40/Annex 52 activities, which include PV installation methods, PV cell type, and electricity generation. The most widely applied RES is the PV system, corresponding to 29 out of a total of 30 cases. Among the roof type PV systems, 71% were non-integrated. In addition, 14 of the 27 cases in which PV systems were applied, satisfied over 100% of the electricity energy demand from the PV system and were found to generate surplus electrical power.

Photovoltaics' architectural and landscape design options for Net Zero Energy Buildings, towards Net Zero Energy Communities: spatial features and outdoor thermal comfort related considerations

AbstractNet Zero Energy Building (NetZEB) design has become a crucial topic of research in recent years. Because of its complexity, discussion has been carried out on methodological criteria useful to define and assess NetZEBs (building system boundary, conversion factors, energy balance, interaction with the grid, monitoring, etc.), mainly with the engineering approach, and a number of case studies worldwide have been investigated. In regard to photovoltaics' (PV) design, research demonstrated the following: (1) PV is an indispensable technology for meeting the net zero energy target; (2) meeting the target of the net zero energy balance at the architectural scale (by using only the surfaces of the building envelope to place renewables) is very difficult and therefore (3) an extension of the balance boundary to a wider scale is needed. That is the concept of NetZEB should be advanced towards the one of Net Zero Energy Communities (NetZECs). In view of such an enlargement of the design domain, this paper investigates architectural and landscape design options (spatial features and outdoor thermal comfort considerations) for PV, on the basis of the analysis of case studies collected and assessed in the framework of the International Energy Agency Solar Heating and Cooling Programme ‐ Energy in Buildings and Communities Programme (SHC‐EBC) Task 40‐Annex 52 Net Zero Energy Solar Buildings. Considering that the traditional understanding of the use of PV in buildings, mainly rooted in technological and morphological considerations, is not sufficient to describe all the issues emerging from this analysis, this paper is a contribution for setting a new cognitive framework in view of PV design for NetZECs. Copyright © 2014 John Wiley & Sons, Ltd.

Applying the building energy simulation test (BESTEST) diagnostic method to verification of space conditioning equipment models used in whole-building energy simulation programs

Validation of building energy simulation programs consists of a combination of empirical validation, analytical verification, and comparative analysis techniques. An analytical verification and comparative diagnostic procedure was developed to test the ability of whole-building simulation programs to model the performance of unitary space-cooling equipment that is typically modeled using manufacturer design data presented as empirically derived performance maps. This procedure is based on the International Energy Agency (IEA) building energy simulation test (BESTEST) diagnostic method and systematically tests whole-building energy simulation software by comparing results from such software to analytical solutions that were developed for the test cases. Field trials of the new procedure were conducted by researchers from nations participating in the IEA Solar Heating and Cooling (SHC) Programme Task 22, using a number of detailed hourly simulation programs from Europe and the US, including: CA-SIS, CLIM2000, ENERGYPLUS, PROMETHEUS, TRNSYS-TUD, and two versions of DOE-2.1E. This article also includes discussion about simulation validation methodologies.

Round robin on accelerated life testing of solar absorber surface durability

As degradation by ageing of solar absorber surfaces was identified to be an important quality factor, the Working Group MSTC (`Materials in Solar Thermal Collectors') of the IEA-SHCP (International Energy Agency-Solar Heating and Cooling Programme) worked out a general test procedure for accelerated lifetime testing (ALT) of these materials, based on methods established by the former Task X of the IEA SHCP. The qualification test procedure was adopted by ISO and is presently dealt within ISO/TC 180 `Solar Energy'. The standard proposal in detail describes a procedure how to test the long-term stability of an absorber surface for the use in flat plate collectors for domestic hot water systems. The collectors service lifetime is assumed to be 25 years, at least. Degradation caused by thermal loads, high humidity and condensation and sulphur dioxide are regarded. In order to examine the feasibility and reproducibility of the test method the Working Group MSTC initiated a round robin test in accelerated life testing of solar absorber surfaces. The test was performed according to the ISO standard proposal dated January 1997. In total, five different industrially manufactured absorber coatings were available to the three participating laboratories. Tests concerning the thermal stability as well as the resistance to high humidity and condensation were performed by all three laboratories. The test for determining absorber surface corrosion resistance to air of high humidity containing sulphur dioxide was carried out by one lab only. The outcome of the round robin test shows very good agreement of the results of the different coatings tested for all of the laboratories. The feasibility and reproducibility of the method was fully confirmed.

Comparing satellite remote sensing and ground network measurements for the production of site/time specific irradiance data

In this article, we compare the accuracy of satellite-derived time/site specific hourly irradiances, with that of irradiances obtained via extrapolation and/or interpolation of nearby ground-measuring stations. A comprehensive study undertaken by the International Energy Agency [Zelenka et al. Final Report of International Energy Agency Solar Heating and Cooling Program (1992)] had addressed this question, but had limited its scope to daily total irradiances. The present study focuses on hourly data.

Building-integrated PV activities within the IEA framework: Going from task 16 to task VII

Early in 1997 a new task will be launched within the scope of the International Energy Agency (IEA) Photovoltaic Power Systems Implementing Agreement. This new task, Task VII, aims to develop building-integrated photovoltaic (BIPV) technology, consider ing technical viability, economics and aesthetic quality. The task concentrates strongly on the involvement of architects, building engineers and urban planners, and the ability to increase their interest in BIPV. Task VII succeeds Task 16, ‘Photovoltaics in Buildings’ of the IEA Solar Heating and Cooling Program, completed in March 1996. It has proved to be very effective in developing and demonstrating new concepts for building-integrated photovoltaics, with t he international cooperation in the task assisting in advancing and promoting the application of photovoltaics in both residential and commercial buildings. Task 16 played a pioneering role in obtaining the World's attention for BIPV. It is expected that Task VII will provide accelerated development and market acceptance of this promising technology.

The thermal performance of advanced glazing materials

Advanced glazing materials offer many opportunities for enhancing the optical and thermal performance of windows and the building envelope. Such materials are being researched because of their recognised potential for energy reduction, increased thermal insulation, solar gain control and improved visual and thermal comfort conditions in residential and commercial buildings. The characterisation of the thermophysical properties of these materials, the measurement of thermal performance, the assessment of appropriate applications and the energy and environmental impacts of their use are the main themes of an international programme of research collaboration being undertaken by the International Energy Agency Solar Heating & Cooling Programme.