Energy-Efficient Self-build Timber Frame House

Energy-Efficient Self-build Timber Frame House

Steve Macken and his wife Deborah run their own wind farm development business, Lomond Energy, from their home just south of Loch Lomond. Given their business interest in renewable energy development, they had a natural and pragmatic desire to develop the property to high energy-effi ciency standards, primarily to control costs and achieve a good return on their investment, but also to reduce their carbon footprint.

Steve Macken and his wife Deborah run their own wind farm development business, Lomond Energy, from their home just south of Loch Lomond. Although the projects they are involved with are UK wide, much of their activity is centred on Scotland. This encouraged them to buy East Cambusmoon Farm, a building in a poor state of repair but with the potential for redevelopment for both home and business use.

Given their business interest in renewable energy development, they had a natural and pragmatic desire to develop the property to high energy-efficiency standards, primarily to control costs and achieve a good return on their investment, but also to reduce their carbon footprint. Steve will readily admit that his expertise is not in designing dwellings, let alone achieving high standards of energy effi ciency, which involves balancing many interrelated design issues. Even for architects, usually required to meet only minimum building regulations standards, this is new territory.

In conjunction with his appointed architect, Thomas Robinson Architects, Steve was keen to find a complete design approach which would take account of all the relevant factors and present him with a manageable number of options. He was very pleased, therefore, to discover the Association of Environment Conscious Builders’ (AECB) design standards (see www.carbonlite.org.uk), which provide a selection of prescribed details underpinned by the tried and tested PassivHaus approach, first developed in Austria and Germany. His goal was to achieve a 70% improvement in energy consumption against the current Scottish building standards. Steve calculated that for the 2500 ft² development, this added only around 3-5% in cost, which would be recouped in a reasonably short time. Having a comprehensive understanding of all the key factors affecting energy performance is extremely beneficial. Realistically, however, most practitioners will need some clear guidance on applying this knowledge effectively, confident that all major issues have been considered within the overall design approach. Fairly early on it became apparent that renovating the original Victorian farmhouse, which was in a very poor state of repair, was not a realistic option, because of the limitations of the building and cost. It was decided to construct a new timber frame house on the same site, which gave far greater flexibility in overall design, layout and materials chosen. The project team took a practical view on energy efficiency vs design requirements. It aimed for and achieved very good standards, which could have been specified to a higher level – but at what cost and risk overall?

This Timber Solutions Case Study considers, therefore, a project from which sound, basic lessons can be learned: It is always better to learn to walk before running. Despite our keen desire to export our sustainability expertise from the UK, we really do need to get some experience under our belt first! The project has achieved acceptable energy goals akin to Level 3 of the Code for Sustainable Homes, a pragmatic starting point for future improvement yet not far short of the PassivHaus standard. At this level you actually achieve a good return on investment, as incremental improvements beyond this standard can present significant risks to budget. This important factor cannot be ignored in our quest for much higher standards of performance. The project made small changes to standard timber frame construction details to achieve significant efficiency gains without the need for specialist building skills and materials. After nearly one year of measuring energy consumption, the results show a 15% improvement on the design values specified. So it works! For a comprehensive historical journey of their self-build project visit http://www.eastcambusmoon.blogspot.com/.

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