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Low/zero energy social housing in UK: a case of under-performance or unintended consequences?

Panel: 5. Energy use in buildings: projects, technologies and innovation

This is a peer-reviewed paper.

Authors:
Mariam Kapsali, Oxford Brookes University, United Kingdom
Rajat Gupta, Oxford Brookes University, School of Architecture, United Kingdom

Abstract

This paper investigates the actual performance and unintended consequences on energy use and environmental conditions of six case study dwellings in three new ‘low/zero’ energy social housing developments in UK, through building performance evaluation techniques comprising: remote monitoring of energy use, end-use demand, environmental conditions and window-opening behaviour, cross-related with forensic data on building fabric and systems’ performance as well as qualitative data gathered through occupants’ surveys and interviews, review of control interfaces and handover guidance. Actual performance is measured for mechanical ventilation systems (with heat recovery (MVHR)) and electricity-generating technologies (solar photovoltaics). The case study houses cover a variety of built forms (end terrace, mid terrace, detached) and construction systems (hempcrete, lightweight steel-frame with pre-insulated panels, and conventional timber frame and brick), but tend to have similar occupancy profiles.

Despite all the developments being designed to high energy standards, the actual energy use exceeds design expectations by a factor of three, questioning the need for whole-house MVHR systems at measured air permeability rates of 6m³/(h.m²) against the design target of 3m³/(h.m²). Lack of proper commissioning of MVHR and heating systems, combined with inadequate user comprehension about their operation and control due to poor guidance during handover, leads to occupant ‘misuse’ wherein systems are de-activated, thereby negatively affecting indoor air quality. A series of unintended consequences occur, such as higher demand temperatures set by occupants, unexpected opening of windows during winters due to under-performance of MVHR combined with habitual behaviours, over-use of heating systems to compensate for higher than expected air permeability, thereby increasing the gap between designed and actual performance. For low/zero houses to perform as intended it is important to tackle these inter-dependencies between building, technology and occupants right from the design stage through to construction, handover and operation.

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Download this paper as pdf: 5-165-15_Kapsali.pdf