Energy Efficiency in practice
Even if you are not environmentally conscious, you’re probably starting to worry about the impact on your wallet when the energy bill comes knocking on your door. Whether its air-conditioning to tackle overheating in recent record temperatures, or central heating through the winter cold snaps, the energy bills are just getting higher. There is, however, a way to mitigate the impact by upgrading your house’s Energy Efficiency – after all, the cheapest energy is that which you don’t use at all!
A project we are currently working on is a prime example of that, where a fabric-first ‘deep retrofit’ is under way.
Our clients have bought an old, but well-kept, two-story cottage near Stroud. The brief was to add a single-story extension and upgrade the existing areas, to add a larger sociable living space and a much more energy efficient house. We used PHPP modelling throughout the design process, informing our design decisions through concept design right into construction detailing. For a good balance between energy performance and construction cost, we focused on two key areas; Insulation and airtightness.
Applying Passivhaus design principles to the detailing of the new extension we have mitigated thermal bridges, fitted triple-glazed windows, super-insulated the fabric and ensured a continuous air-tightness layer. At the same time we’re adding internal wall, roof and floor insulation to the existing portion of the house as well as replacing existing windows with new, better preforming ones, significantly reducing heat losses.
Designing to the principles of Passivhaus is not only great for energy efficient design, but it also creates a really comfortable living environment with the completed building maintaining an almost constant temperature year-round, draft-free with constant filtered fresh air and almost no noise from outside. We have sought to use natural or recycled materials where possible, which also helps to create a healthy internal environment. Wood fibre insulation is used everywhere above ground; we love it for its breathability, versatility and low environmental impact – indeed using timber for framing and insulation is CO2-negative. We’ve even replaced plasterboard with woodwool sheets. Recycled foamed glass insulates the floor and we’re using lime mortar, lime render and limecrete – we’re loving the lime, its great for moisture control and it absorbs CO2 throughout its working like.
Timber cladding has been sourced locally and ethically in the South West, reducing embodied carbon. This thermally modified Ash cladding puts a use to the die-back felling there’s been so much of lately; it should last 50 years, and it will sliver down quickly to complement the colour of the local stone.
Whilst using Passivhaus ideas and modelling we have designed this project to meet the AECB Retrofit Standard, and it’s aligned to our targets for the RIBA 2030 Climate Challenge. We’re proud of this project for its all-round sustainable credentials, as well as for the design’s partnering of a traditional and cosy cottage with a crisp modern extension.
We will give you an update on this lovely project once it is near completion. Stay Tuned!
