An investigation into the overheating risk in low-energy new-built homes

Recently, overheating in British housing has received increased attention due to climate change and consequent impact on the thermal comfort and the health of building occupants. The risk of overheating becomes even larger considering the requirements for higher insulation and airtightness levels set by building regulations. Passive design strategies, such as the use of thermal mass and ventilation, for regulating indoor temperatures may improve the thermal comfort of occupants without the use of energy intensive equipment. Modern Methods of Construction (MMC) are expected to play a significant role in the future outputs of the housing construction sector. However, MMC, which generally present low levels of thermal mass, are treated with scepticism by designers since they are considered to be more prone to overheating compared to masonry constructions. Due to the lack of extensive research data on the thermal performance of these systems, however, it can be inferred that concerns may be based on the perception of the industry rather than actual data. Therefore, the work presented in this thesis investigated the risk of overheating in dwellings built with MMC. The analysis considered the performance of the constructions from various perspectives following a route from the general investigation to the more specific characteristics of the building elements. First, an investigation of the zone temperatures obtained through monitoring and through whole building dynamic simulations was performed, in an attempt to evaluate the relative performance of different construction types and building elements. Next, the interaction of the various building elements with their surrounding space was assessed through monitoring the heat flows and the temperatures on the surface of these elements in situ. Finally, a more detailed investigation of the dynamic characteristics of these elements under fixed conditions was conducted through laboratory testing and Finite Element Analysis (FEA). A parametric simulation study of ambient temperatures in a timber frame building considered the potential to use non-traditional materials for regulating internal temperatures. Results showed that overheating was an issue in most of the zones examined for the conventional timber frame construction. The use of additional materials resulted in reduced overheating levels of up to 85% in some cases; this evidence may be used to inform designers when considering measures to reduce the overheating risk of MMC. In another study of two houses built with different construction methods, it was found that the timber frame and modern masonry walls had very similar performance, with the latter presenting slightly reduced levels of overheating in some cases (up to 12% lower compared to timber frame). Monitoring the heat flows at the surface of the building elements in situ as well as through laboratory testing and FEA showed that difference in performance between masonry constructions and MMC was not always as clear as expected from the construction characteristics of the elements. It was clear that conventional masonry constructions do not benefit fully from the increased mass and had comparable performance with some MMC. Phase Change Materials (PCM) were also found more responsive than conventional plasterboard in situ, although some discrepancy compared to the theoretical performance was identified. The findings of this study may be useful for designers so that optimum use of the benefits of thermal mass is made

Investigating the potential of adding thermal mass to mitigate overheating in a super-insulated low-energy timber house

Evidence suggests that many UK dwellings are subjected to overheating or will be at some point in the future. Dwellings built using modern methods of construction may have a higher overheating risk due to the low levels of thermal mass associated with most of these methods. The Nottingham HOUSE, a prefabricated timber modular building designed to zero-carbon and Passivhaus standards, was examined in terms of overheating occurrence. The ability of a high-density fibreboard and phase change materials to provide additional levels of thermal mass was examined with the results suggesting that these can help regulate internal temperatures with the benefit of being easy to integrate

Field testing of the QUB method for assessing the thermal performance of dwellings: In situ measurements of the heat transfer coefficient of a circa 1950s detached house in UK

In this paper the findings from a long-term field study of the thermal performance of a circa 1950s dwelling are presented and discussed. The study aimed at evaluating the robustness of the QUB method in the field under UK climatic conditions. A series of 147 QUB tests were performed during the whole heating period (September 2016 – March 2017) in a detached house located in the University Park campus, University of Nottingham considering two distinct conditions: as-built and with increased airtightness. The QUB method was able to provide consistent and robust estimates of the Heat Transfer Coefficient (HTC) of the whole dwelling with approximately 80% of the results within ±10% from the mean and more than 95% of the results within ±15%. The need to treat heat losses occurring through the ground when assessing the thermal performance of buildings through experimental diagnostics methods was highlighted, especially in uninsulated concrete slab floors. The method devised to isolate the ground floor heat losses from the whole building losses resulted in reduced dispersion of the adjusted Heat Transfer Coefficient with a coefficient of variation of 5% and 98% of results within ±10% from the mean

RINNO: Towards an Open Renovation Platform for Integrated Design and Delivery of Deep Renovation Projects

The building stock accounts for a significant portion of worldwide energy consumption and greenhouse gas emissions. While the majority of the existing building stock has poor energy performance, deep renovation efforts are stymied by a wide range of human, technological, organisational and external environment factors across the value chain. A key challenge is integrating appropriate human resources, materials, fabrication, information and automation systems and knowledge management in a proper manner to achieve the required outcomes and meet the relevant regulatory standards, while satisfying a wide range of stakeholders with differing, often conflicting, motivations. RINNO is a Horizon 2020 project that aims to deliver a set of processes that, when working together, provide a system, repository, marketplace and enabling workflow process for managing deep renovation projects from inception to implementation. This paper presents a roadmap for an open renovation platform for managing and delivering deep renovation projects for residential buildings based on seven design principles. We illustrate a preliminary stepwise framework for applying the platform across the full-lifecycle of a deep renovation project. Based on this work, RINNO will develop a new open renovation software platform that will be implemented and evaluated at four pilot sites with varying construction, regulatory, market and climate contexts

An investigation into the overheating risk in low-energy new-built homes

Recently, overheating in British housing has received increased attention due to climate change and consequent impact on the thermal comfort and the health of building occupants. The risk of overheating becomes even larger considering the requirements for higher insulation and airtightness levels set by building regulations. Passive design strategies, such as the use of thermal mass and ventilation, for regulating indoor temperatures may improve the thermal comfort of occupants without the use of energy intensive equipment. Modern Methods of Construction (MMC) are expected to play a significant role in the future outputs of the housing construction sector. However, MMC, which generally present low levels of thermal mass, are treated with scepticism by designers since they are considered to be more prone to overheating compared to masonry constructions. Due to the lack of extensive research data on the thermal performance of these systems, however, it can be inferred that concerns may be based on the perception of the industry rather than actual data. Therefore, the work presented in this thesis investigated the risk of overheating in dwellings built with MMC. The analysis considered the performance of the constructions from various perspectives following a route from the general investigation to the more specific characteristics of the building elements. First, an investigation of the zone temperatures obtained through monitoring and through whole building dynamic simulations was performed, in an attempt to evaluate the relative performance of different construction types and building elements. Next, the interaction of the various building elements with their surrounding space was assessed through monitoring the heat flows and the temperatures on the surface of these elements in situ. Finally, a more detailed investigation of the dynamic characteristics of these elements under fixed conditions was conducted through laboratory testing and Finite Element Analysis (FEA). A parametric simulation study of ambient temperatures in a timber frame building considered the potential to use non-traditional materials for regulating internal temperatures. Results showed that overheating was an issue in most of the zones examined for the conventional timber frame construction. The use of additional materials resulted in reduced overheating levels of up to 85% in some cases; this evidence may be used to inform designers when considering measures to reduce the overheating risk of MMC. In another study of two houses built with different construction methods, it was found that the timber frame and modern masonry walls had very similar performance, with the latter presenting slightly reduced levels of overheating in some cases (up to 12% lower compared to timber frame). Monitoring the heat flows at the surface of the building elements in situ as well as through laboratory testing and FEA showed that difference in performance between masonry constructions and MMC was not always as clear as expected from the construction characteristics of the elements. It was clear that conventional masonry constructions do not benefit fully from the increased mass and had comparable performance with some MMC. Phase Change Materials (PCM) were also found more responsive than conventional plasterboard in situ, although some discrepancy compared to the theoretical performance was identified. The findings of this study may be useful for designers so that optimum use of the benefits of thermal mass is made

Evaluation of the precision and accuracy of the QUB/e method for assessing the as-built thermal performance of a low-energy detached house in UK

In this paper, the findings from a field study of the thermal performance of a low-energy dwelling are presented and discussed. The study aimed at evaluating the precision and accuracy of the QUB/e method in the field under UK climatic conditions. A series of in situ measurements were carried out in a low-energy detached house located in the University Park campus, University of Nottingham to determine both the whole building Heat Transfer Coefficient (HTC) and the thermal transmittances (U-values) of the external walls and the glazings. The values determined with well-established quasi-static measurement methods (coheating test, ISO 9869-1 average method) were used as reference (benchmark) values to assess the accuracy of the QUB/e method. In total 18 consecutive QUB/e tests were conducted.The QUB/e method was able to provide precise and accurate estimates of the whole building HTC: 94% of the results (i.e. 17 out of 18) were found to be within 15% from the mean and 78% of the HTC estimates (i.e., 14 out of 18) obtained with a QUB/e test could not be considered statistically different from the HTC determined with the coheating test (benchmark). It should be noted that the reported confidence intervals associated with the HTC estimates obtained with the QUB/e tests were slightly larger than the one reported for the coheating test (i.e., 11.6% in average and 6.1%, respectively). The Mean Bias Error (MBE) and the Root Mean Square Error (RMSE) associated with the HTC estimates obtained with the QUB/e tests were approximately 11%.The QUB/e method was also able to provide precise and accurate estimates of the thermal transmittances of the external walls and the glazings. We observed that all but seven (i.e., 119 out of 126 or 94%) U-values estimates of the external walls obtained with a QUB/e test could not be considered statistically different from the U-values determined with the ISO 9869-1 average method (benchmark). With regard to the glazings, this was observed for all U-values estimates (i.e., 162 out of 162 or 100%). It should be noted that the reported confidence intervals associated with the U-value estimates obtained with both test methods were close (i.e., approximately 10% in average) for all elements except for the ICF wall

The Nexus between Market Needs and Value Attributes of Smart City Solutions towards Energy Transition. An Empirical Evidence of Two European Union (EU) Smart Cities, Evora and Alkmaar

This study presents an experiential process and a market-oriented approach for realizing cities' energy transition through smart solutions. The aim of this study is twofold: (a) present a process for defining a repository of innovative solutions that can be applied at building, district, or city level, for two European Union cities, Evora and Alkmaar, and support the deployment of positive energy districts enabling a sustainable energy transition, and (b) understand in a systematic way the attributes of value offered by energy-related smart city solutions, in order to facilitate the development of sustainable value propositions that can successfully address city needs. The repository is assessed against four elements of value, which include social impact, life-changing, emotional, and functional attributes, according to the value pyramid of Maslow. Results show that the value attributes of quality, motivation, integration, cost reduction, information, and organization are highly relevant to the proposed smart solutions. The results presented in this study are useful for city planners, decision-makers, public bodies, citizens, and businesses interested in designing their energy transition strategy and defining novel technologies that promote urban energy sustainability