Established in 2011, Sam Foster Architects (SFA) specialises in contemporary ecological architecture. In all of their projects, they aim to help clients to create warm, bright and energy efficient places to inhabit and use, and to make sure that these are long lasting and robust.
In current practice, retrofit measurements are undertaken without a clear knowledge of existing performance. SFA were looking to develop their capacity to undertake and commission building performance evaluation (BPE), and to use this knowledge to inform design processes.
Funded by a Scottish Funding Council Innovation Voucher, administered by Interface, Sam Foster Architects collaborated with the Mackintosh Environmental Architecture Research Unit at the Glasgow School of Art to undertake a Building Performance Evaluation process that would develop an evidence-based design approach. An understanding of BPE would complement SFA’s existing expertise in sustainable architecture, and improve the practice’s ability to win commissions.
There was an opportunity to undertake the collaborative project as part of a proposal to refurbish an existing, single storey mid-19th century building to improve its energy efficiency, create appropriate conditions for the storage and display of exhibition materials and reduce carbon dioxide emissions from the heating and lighting systems. The building is owned and run by Arisaig Community Trust, which has increased visitor numbers from less than 1,000 per year to over 10,000 within their two year ownership. The existing building was refurbished and extended around 1999 but suffered from excessive heat loss and draughts, resulting in high heating costs and CO2 emissions.
There were two separate but linked contexts for the project: the first was the requirement by the Scottish Government for carbon dioxide emissions from buildings to reduce significantly to help reduce the effects of climate change; the second was the ongoing work of built heritage organisations such as Historic Scotland (HS) and the Society for the Protection of Ancient Buildings (SPAB) to develop knowledge on sustainable appropriate ways of refurbishing buildings of traditional construction. With over 80% of the 2050 building stock already existing, the need to address energy efficient refurbishment of existing buildings was crucial, and this represented an important market for SFAs services.
The existing building used in this project – 19th century stone construction refurbished within the last 20 years – represented a very common typology, both in the immediate area and around Scotland. It was expected that the work to refurbish (using best practice guidance and methodology) a building that was previously refurbished would be of direct relevance and interest both to organisations such as HS and SPAB, and to homeowners and residents of similar buildings.
Architects generally do not have a clear idea about how buildings perform, or how retrofit measures will affect performance. This project collected information about how the existing building was working, and used this to inform design decisions. The knowledge generated was then used to make a ‘before and after’ comparison of performance. The aim of the project was to demonstrate the benefits of this type of approach, not only in terms of improving design decisions, but also to verify these. There are very few case studies and examples illustrating how best to improve the energy efficiency of a previously refurbished building. Involvement in this project will give SFA a competitive advantage when bidding for similar types of projects in the future.
The project helped Sam Foster Architects determine the most appropriate methods of refurbishing the building, as well as offering guidance on how to deal with similar future projects.
It provided MEARU with key source data on the energy and environmental performance of a traditional building that is typical of many in Scotland, and this will be used as the basis for academic publications.
It will benefit the Scottish economy by providing an evidence base for a design standard that can help organisations such as Historic Scotland and SPAB to offer guidance on the most appropriate methods and materials to use in this type of refurbishment.
There were two direct impacts of the project in the village where the building is located:
- The BPE-related pre-works gave clear benchmarks against which to compare the refurbished building. The client-funded post-works airtightness test confirmed that draughts in the building had been reduced by 91% and they were then able to heat the building to a comfortable temperature. Through site visits and awareness raising events by Arisaig Community Trust (who own the building) it was demonstrated to village residents the potential improvements in comfort and reduction in fuel costs.
- The BPE has formed part of a wider project being run by Arisaig Community Trust to help reduce residents’ home energy costs. The data presented through the BPE report has added weight and gravitas to the Trust’s initiatives, essentially leading by example.
MEARU’s academic input on the refurbishment of the Land, Sea & Islands Centre was invaluable in helping us to develop a clear understanding of the thermal performance of the existing building. Their measurements and analysis provided us with the information necessary to adjust our refurbishment measures – increasing insulation in areas of higher heat loss and reducing insulation elsewhere, for example – to make most effective use of the budget. Through MEARU’s continued involvement post-refurbishment we now have an explicit, quantitative picture of the extent of the improvements that have been achieved. This includes thermal imaging that clearly shows a high reduction in thermal bridging, airtightness testing that demonstrates a major reduction in heat loss through infiltration, and energy use figures that are significantly lower than before the refurbishment took place. Their input has also demonstrated that building elements such as walls and roofs commonly do not perform as desktop u-value calculations suggest, making in-situ measurement invaluable in helping to determine appropriate refurbishment solutions. Sam Foster