An Investigation of Climatically Responsive Ultra-Low Energy Housing in Rural Scotland: a Case Study
In rural Scotland there has been a trend over the last 40 years towards mass market housing development which employs standardised housing models and suburban planning layouts. These have little relationship to rural landscape characteristics, regional climatic variations or historic rural communities. While they comply with current building standards, they fall significantly short of proposed improvements for energy performance which require all new homes to be ‘Zero Carbon’ by 2016/17 if practical and the European target of ‘Nearly Zero Energy Homes’ by the end of 2020. It is recognised that changes in legislation to reach these targets are falling behind schedule and energy analysis methods are flawed due to outdated calculation methodologies and imprecise climate data. This research firstly provides an in-depth context for rural housing provision outlining the drivers and legislative requirements. The first section of the literature review investigates planning and current practice in housing, whilst the second section outlines the requirements for improved energy efficiency from the European to Scottish contexts. The research then goes on to quantify the effects of regional climatic variation, in nine areas across Scotland, on space heating energy demand (SSHD). It utilises a best practice ultra-low energy housing prototype to demonstrate the requirement for regional solutions. All of the studies use a customised version of the Passivhaus Planning Package, an industry leading energy quantification methodology for heating energy calculations. A series of studies define the design envelope for achieving regional solutions by quantifying the relationship between the variation of design and form on the SSHD in the extremes of the Scottish regional climates. The variables relate to common metrics: orientation, glazing areas, roof forms and building typology. A separate study also compares the effect of Zero Carbon Homes and Passivhaus performance specification on SSHD. This method is developed further to determine the effect of building design on SSHD and heat load using seven contemporary Scottish Government exemplar housing designs. Improvements to the energy efficiency of these designs are made by considering variations to orientation and glazing design which are then discussed in relation to their impact on design quality. The results of the research demonstrate an increase of 81% in SSHD caused by regional variation across Scotland with up to a 29% increase from the UK average climate used in the UK’s legislative analysis method SAP. This requires significant increases in insulation levels to retain SSHD performance. Alterations to the buildings orientation demonstrate an increase of 165% SSHD when deviating 180° from south, which is significantly higher than guidance suggests. The analysis of existing exemplar designs demonstrate a threefold increase in SSHD due to building form and orientation in some designs. The optimisation of the same designs illustrates a 45% reduction in SSHD through improved orientation and glazing design. This thesis contributes to improving design thinking and assessment methodologies for new rural Scottish housing by highlighting the importance of climatically responsive design along with the consideration of appropriate energy efficient forms. The results of the thesis contribute to the debate surrounding the appropriate response of new housing in rural Scottish environments and highlights the importance of regional approaches and passive solar design for reduced housing energy use. This thesis contributes original knowledge on the effects of Scottish climate and building form on the SSHD of ultra-low energy housing in Scotland. The extent to which a number of principle architectural planning and design parameters can be varied and optimised across different climatic regions will give architects and designers a more quantitative understanding of their design decisions and impact on space heating energy performance across Scotland.
Passivhaus, Low energy housing, Architecture, Rural, Scotland
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