Type – 4 bed timber framed detached house, built 2007.

Size 220 m2 approx

Owners  Sally Williams and David Browne

Features

Timber frame construction (natural preservative)

Sustainably sourced timber

Warmcell recycled paper insulation

Solar thermal hot water and solar PV

Green roof using Sedum plants

Dual flush lavatories and showers in lieu of baths – one included

Underfloor heating with individual room thermostats

Double glazed timber windows with coloured aluminium facings for low maintenance

Clay paint  internal wall finish

 Energy use

Electricity used – 4913 kWh (excludes out-buildings, which are separately metered)

Electricity generated – 4kW system installed July 2012 and fed to house.

Gas – 3225 kWh

CO2 Emissions – 4.29 tonnes pa (SAP 2005) From National Energy Foundation calculator 3.17 tonnes pa with average per household of 5.56 tonnes per annum

EPC Rating – B

 Lessons

Internal wall finishes – Opted to use clay paint throughout to reduce VOCs and contribute to breathing wall. If used in areas that need to be wiped down/cleaned requires sealing with wax. Other products have now been developed that offer better durability.

Lighting – Low energy lamps are installed throughout with the exception of the staircase, upstairs corridor and augmented lighting in the kitchen area. These take a while to warm up for their full output to be reached and additional fittings are required to reach a decent level of general lighting. The lamps need to be specially disposed of/recycled. Technology has moved on and LEDs are preferred.

Mechanical services – Each room has its own programmable thermostat. Although this is desirable and enables micromanagement of room use and orientation compensation it does require a commitment from the inhabitants to optimise the installation. Equally, manifolds for underfloor heating, expansion vessels for solar thermal etc can be space hungry and need to be designed in: even then there can be a few surprises!

Green roof – green roofs are lovely and that goes for walls too. There is a level of maintenance – weeding/feeding – so ensuring access is possible and safe for preferably an annual inspection. Using this solution makes rainwater re-cycling more complicated due to the additional growing medium and plant material that is washed off, so we forfeited this technology. Looking ahead, water collection will be increasingly important. We have included a pond in our garden, at the low point to collect water and continue to encourage wildlife habitats.

Sound insulation – Internal sound insulation is limited and care needs to be taken to get this right in low mass structures such as timber framing, especially between floors. This is exacerbated by our choice to not use carpets upstairs.

Wall insulation – The recycled Warmcell insulation was wet applied to minimise the effects of settlement over time. It would be interesting to carryout thermal imaging to see how the installation has fared.

Foundations – The subsoil is sandy/clay. We explored the possibility of including a basement as this was seen as a way of reducing impact above ground whilst optimising the building opportunity. This was vetoed on the risk of de-watering. Piled foundations were required, which also meant that it was not possible to re-use any of the existing sub-structures or walls in the design.

Access – A designated bridleway provides the principal access to the site, so our solution needed to use small components. Where supplies deliveries could only be made by large lorries, local arrangements were negotiated for the load to be broken down and materials transferred by suitable transport. This added cost to deliveries generally, skip hire, concrete loads etc. A system build/offsite construction would really have been challenging!

Inspirational reading – ‘Cradle to Cradle – Remaking the way we make things’ by Michael Braungart and William McDonough, and a recent re-visit to ‘House’ by Tracy Kidder

 

Contractors

Building :          Dermot Burton, Westmeston Place, Westmeston,

Solar thermal: Rayotec

Solar PV:          Affinitus Energy Systems