Building integration of domestic solar combi-systems: The importance of managing the distribution pipework

This paper examines the inextricable link between the performance of solar combi-systems coupled with under-floor radiant heating and the architectural design of buildings where such systems may be used. It focuses on the impact of building fabric, area and rooms’ layout on both the system‘s performance and thermal comfort. The building integration of the distribution pipework is sensitively examined through an experimental analysis of a case study; a residence in South Europe, using dynamic thermal simulation and numerical modeling. It is found that pipe losses - regarded both as energy wastage and heat gains to the space - can be significant but also controlled if the pipe network is carefully planned. The results show that collector loop losses can be comparable to tank losses for most of the year or even higher in some months, and that the management of the collector loop piping length can be more effective in controlling these losses than improving the pipes’ insulation. The analysis further shows that there are times when distribution losses have the potential to cause noticeable local overheating e.g. long piping length or piping route passing through narrow spaces like corridors and lobbies

Latent heat storage in building elements: a systematic review on properties and contextual performance factors

A systematic review of latent heat storage in building elements was conducted to establish the current knowledge base and reveal key design and performance factors that could be used to define technologies available for immediate implementation and for specific applications. All relevant literature published by April 2014 was critically evaluated and a data extraction procedure was used to organise, analyse and report design and performance parameters of Phase Change Material (PCM) elements. The review of a total of 120 papers revealed that published information on these aspects is diverse and in many cases insufficient. The diversity of test conditions and variety of reported values indicate that physical properties and performance data concerning materials and complete PCM elements are not directly comparable. Therefore matching technologies and applications for specific climates and building typologies is not possible solely through published information. However evidence was collected which shows that, with appropriate design, PCM elements can contribute to reducing loads and achieving energy savings in buildings, while securing a comfortable indoor environment. Key design factors to this end were found to be the climate and target season, the design of appropriate controls for active and passive systems used in combination with the PCM elements and cost-related factors. The review also mapped the research foci to date, revealing the range of variations previously examined and potential research gaps worth pursuing in the future

Potential for solar thermal technologies and thermal energy storage to reduce the energy use from Welsh housing

This thesis deals with the potential contribution that state-of-the-art solar thermal (ST) systems enhanced by thermal energy storage (TES) technologies might have in reducing the energy use in Welsh dwellings. The focus of this work lies with the share of the overall amount of conventional energy currently consumed for thermal comfort and hot water preparation that could be replaced by solar energy harvested by active, water-based, solar systems. Twelve typical Welsh dwellings drawn from a recent survey and considered as representative of the Welsh housing stock are modelled and the solar collectors' yield for different orientations and tilts is predicted. The subject is investigated with computer simulations using the TRNSYS simulation engine. The methodology dictates at first prediction and analysis of the thermal energy demand profiles of 12x4 case studies using average (smoothed) and actual (warmer) weather conditions, continuous and intermittent comfort maintenance. Next the ST potential is estimated considering solely a maximum (0.7) and an average (0.4) overall system efficiency and no other technical part for the ST system (modelling approach), in order to investigate the mismatch of energy demand and availability and the TES contribution. The performance characteristics of some representative European ST systems (short-term TES only), as derived from the IEA SHC Task 26 FSC method, are then applied to the simulations to reveal the potential with realistic losses and parasitic energy consumption included (applied only to 5 compatible models). It is revealed that all these house types are possible candidates for effective ST applications, assuming that economies of scale would allow for large absorber areas in the near future. The modelling approach shows that ST systems could contribute to thermal savings between 9%-34% solely with direct utilisation of the collected energy. Furthermore, for most cases, if reasonable sized stores would be used (up to 300kWh TES capacity) then the solar contribution to the overall thermal energy consumption, in the most favourable conditions, would be around 42-58%. Only a couple of models appear to have a lower potential, mainly due to lack of sufficient absorber areas. However for reaching the highest end of expectations for certain house types---up to 54% with average and up to 100% with warmer weather conditions---inter-seasonal storage would be required. In this case, the justifiable storage capacities predicted correspond to very large store volumes, revealing that these are currently not feasible options, as sensible heat storage is still the state-of-the-art for TES. Use of innovative storage types identified by the literature survey, that would only be available in the future, are required in order to achieve high solar contributions, considering space limitations in Welsh dwellings. The FSC results show that for the 5 models the use of solar energy would bring thermal energy savings of around 41-47% if the best system is employed compared to a conventional system, while if parasitic (electric) energy consumption is considered the expected energy savings could be as low as 10%. The actual ST potential is analysed and is found to be in between the two approaches, as both methods have advantages and limitations and complement each other.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The potential for solar thermal technologies and thermal energy storage to reduce the energy use from Welsh housing

This thesis deals with the potential contribution that state-of-the-art solar thermal (ST) systems enhanced by thermal energy storage (TES) technologies might have in reducing the energy use in Welsh dwellings. The focus of this work lies with the share of the overall amount of conventional energy currently consumed for thermal comfort and hot water preparation that could be replaced by solar energy harvested by active, water-based, solar systems. Twelve typical Welsh dwellings drawn from a recent survey and considered as representative of the Welsh housing stock are modelled and the solar collectors' yield for different orientations and tilts is predicted. The subject is investigated with computer simulations using the TRNSYS simulation engine. The methodology dictates at first prediction and analysis of the thermal energy demand profiles of 12x4 case studies using average (smoothed) and actual (warmer) weather conditions, continuous and intermittent comfort maintenance. Next the ST potential is estimated considering solely a maximum (0.7) and an average (0.4) overall system efficiency and no other technical part for the ST system (modelling approach), in order to investigate the mismatch of energy demand and availability and the TES contribution. The performance characteristics of some representative European ST systems (short-term TES only), as derived from the IEA SHC Task 26 FSC method, are then applied to the simulations to reveal the potential with realistic losses and parasitic energy consumption included (applied only to 5 compatible models). It is revealed that all these house types are possible candidates for effective ST applications, assuming that economies of scale would allow for large absorber areas in the near future. The modelling approach shows that ST systems could contribute to thermal savings between 9%-34% solely with direct utilisation of the collected energy. Furthermore, for most cases, if reasonable sized stores would be used (up to 300kWh TES capacity) then the solar contribution to the overall thermal energy consumption, in the most favourable conditions, would be around 42-58%. Only a couple of models appear to have a lower potential, mainly due to lack of sufficient absorber areas. However for reaching the highest end of expectations for certain house types---up to 54% with average and up to 100% with warmer weather conditions---inter-seasonal storage would be required. In this case, the justifiable storage capacities predicted correspond to very large store volumes, revealing that these are currently not feasible options, as sensible heat storage is still the state-of-the-art for TES. Use of innovative storage types identified by the literature survey, that would only be available in the future, are required in order to achieve high solar contributions, considering space limitations in Welsh dwellings. The FSC results show that for the 5 models the use of solar energy would bring thermal energy savings of around 41-47% if the best system is employed compared to a conventional system, while if parasitic (electric) energy consumption is considered the expected energy savings could be as low as 10%. The actual ST potential is analysed and is found to be in between the two approaches, as both methods have advantages and limitations and complement each other

Using solar screens in school classrooms in hot arid areas: the effect of different perforation on daylighting levels

Hot arid areas are endowed with an abundance of clear skies. Thus, the solar energy available can significantly raise the temperature of interior spaces and also result in an uncomfortable visual environment due to glare and poor uniformity ratios. This paper focuses on a special case of girls’ schools in Saudi Arabia, where the privacy issue is critical due to socio-cultural and religious beliefs. Most windows in girls’ schools are covered by dark opaque film to maintain privacy. This window treatment brings the need for electric lights, which makes schools huge consumers of energy considering the peak time operational hours and the large number of schools. This paper looks at how different perforation rates affect the performance of screens by simulating 10 different ratios from 10% to 90% and a base case without a screen. First, the effect was tested on average illuminance levels, and then on Daylight Availability by using the Daylight Dynamic Performance Metrics approach (DDPM). The results specify the minimum perforation rate to provide the required average illuminance in each orientation and give a tool to decide perforation rates according to the required percentage of daylit area in contexts similar to the studied space

Potential for solar thermal technologies and thermal energy storage to reduce the energy use from Welsh housing

This thesis deals with the potential contribution that state-of-the-art solar thermal (ST) systems enhanced by thermal energy storage (TES) technologies might have in reducing the energy use in Welsh dwellings. The focus of this work lies with the share of the overall amount of conventional energy currently consumed for thermal comfort and hot water preparation that could be replaced by solar energy harvested by active, water-based, solar systems. Twelve typical Welsh dwellings drawn from a recent survey and considered as representative of the Welsh housing stock are modelled and the solar collectors' yield for different orientations and tilts is predicted. The subject is investigated with computer simulations using the TRNSYS simulation engine. The methodology dictates at first prediction and analysis of the thermal energy demand profiles of 12x4 case studies using average (smoothed) and actual (warmer) weather conditions, continuous and intermittent comfort maintenance. Next the ST potential is estimated considering solely a maximum (0.7) and an average (0.4) overall system efficiency and no other technical part for the ST system (modelling approach), in order to investigate the mismatch of energy demand and availability and the TES contribution. The performance characteristics of some representative European ST systems (short-term TES only), as derived from the IEA SHC Task 26 FSC method, are then applied to the simulations to reveal the potential with realistic losses and parasitic energy consumption included (applied only to 5 compatible models). It is revealed that all these house types are possible candidates for effective ST applications, assuming that economies of scale would allow for large absorber areas in the near future. The modelling approach shows that ST systems could contribute to thermal savings between 9%-34% solely with direct utilisation of the collected energy. Furthermore, for most cases, if reasonable sized stores would be used (up to 300kWh TES capacity) then the solar contribution to the overall thermal energy consumption, in the most favourable conditions, would be around 42-58%. Only a couple of models appear to have a lower potential, mainly due to lack of sufficient absorber areas. However for reaching the highest end of expectations for certain house types---up to 54% with average and up to 100% with warmer weather conditions---inter-seasonal storage would be required. In this case, the justifiable storage capacities predicted correspond to very large store volumes, revealing that these are currently not feasible options, as sensible heat storage is still the state-of-the-art for TES. Use of innovative storage types identified by the literature survey, that would only be available in the future, are required in order to achieve high solar contributions, considering space limitations in Welsh dwellings. The FSC results show that for the 5 models the use of solar energy would bring thermal energy savings of around 41-47% if the best system is employed compared to a conventional system, while if parasitic (electric) energy consumption is considered the expected energy savings could be as low as 10%. The actual ST potential is analysed and is found to be in between the two approaches, as both methods have advantages and limitations and complement each other.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Using solar screens in school classrooms in hot arid areas: The effect of different aspect ratios on daylighting levels

Hot arid areas are endowed with an abundance of clear skies. Thus, the solar energy available can significantly raise the temperature of interior spaces and also result in an uncomfortable visual environment. External perforated solar screens have been used to control solar penetration through windows. Such screens can also serve a social function, that of maintaining privacy. This paper focuses on a special case of girls’ schools in Saudi Arabia, where the privacy issue is critical due to socio-cultural and religious beliefs. Windows in girls’ schools facing public spaces are typically covered by dark opaque film to maintain privacy. This window treatment results in overreliance on artificial lighting, and in a corresponding increase in energy use. The performance of screens can be affected by many parameters, namely: perforation rate, depth ratio, shape, reflectivity of colour, aspect ratio of openings. This paper looks at how different Aspect ratios affect the performance of screens by simulating a range of cases of different aspect ratios, using the Daylight Dynamic Performance Metrics approach (DDPM). Results recommend using 1:1 aspect ratio for the south orientation whereas using different aspect ratios for the North and West orientations provide better daylight levels in the studied context

The implications of demand response measures and electrification of transport on UK household energy demand and consumption

This study has been undertaken to gain a better understanding on how the residential electricity demand and consumption values might evolve in the medium term in a future built environment benefiting from renewable energy systems and storage technologies. Analysis and modeling of winter and summer electricity demand and consumption data in four scenarios for 2030 was performed, after the establishment of a baseline scenario in 2015 (BS 2015). The scenarios in 2030 included the business as usual scenario (BAU 2030), a scenario assuming electrification of heating and energy efficiency measures (EE 2030), a scenario in which demand response measures are also considered (DR 2030) and a scenario in which one electric vehicle (EV) is assumed for each house as well (Te 2030). Electricity demand and consumption ranges for different scales at the distribution level for each scenario were derived. It was concluded that properties with currently low peak demand values are bound to experience a much higher peak in the early morning hours in winter under the Te 2030 scenario than properties with already high peak demand. This would signify a new peak at a new time. In terms of electricity consumption in 2030, the energy efficiency measures would counterbalance the increase of electricity consumption due to the inclusion of the EV in winter, so the consumption in Te 2030 is found to be similar to the consumption in BAU 2030. The analysis also demonstrated the need to explore the potential role of thermal storage versus electricity storage in buildings

Using solar screens in school classrooms in hot arid areas: the effect of different perforation on daylighting levels

Hot arid areas are endowed with an abundance of clear skies. Thus, the solar energy available can significantly raise the temperature of interior spaces and also result in an uncomfortable visual environment due to glare and poor uniformity ratios. This paper focuses on a special case of girls’ schools in Saudi Arabia, where the privacy issue is critical due to socio-cultural and religious beliefs. Most windows in girls’ schools are covered by dark opaque film to maintain privacy. This window treatment brings the need for electric lights, which makes schools huge consumers of energy considering the peak time operational hours and the large number of schools. This paper looks at how different perforation rates affect the performance of screens by simulating 10 different ratios from 10% to 90% and a base case without a screen. First, the effect was tested on average illuminance levels, and then on Daylight Availability by using the Daylight Dynamic Performance Metrics approach (DDPM). The results specify the minimum perforation rate to provide the required average illuminance in each orientation and give a tool to decide perforation rates according to the required percentage of daylit area in contexts similar to the studied space