Durrants were recently invited to attend an event by CLA East to show how a 25 year old chicken shed was converted to a zero-carbon home. Nick Woolley and his wife Saffy shared with Durrants Principal Planner, Jonny Rankin, the challenges and successes they faced during the conversion process.
Planning permission initially came to life via a Class Q Prior Approval, which will be very familiar to Durrants clients. Class Q’s are a Building Consultancy mainstay, with several on the books at any one time.
The chicken shed in question benefitted from a southern elevation allowing for passive solar gain and a large bank of solar panels on the south-facing roof slope.
Having attended events at Woolley’s old HQ in Freckenham, I was aware of Nick’s advocacy for the Hockerton Housing project and the building principles therein. Having retrofitted the previous Old Rectory buildings, in speaking with Nick, I could sense the excitement at the opportunity to start from the ground up – literally – with the chicken shed. Some features we had the pleasure to view included:
- 300mm thick floor concrete at 300mm, giving an overall ‘U’ value of 0.1*;
- 300mm of floor to ceiling wall insulation, also giving an overall ‘U’ value of 0.1;
- Triple glazed windows;
- Epoxy resin wall ties (not steel) preventing thermal losses; and
- 440mm of insulation under roofing sheets giving a ‘U’ value of 0.055.
Onsite generation is key to the success of the zero-carbon performing home and we were abvle to view the 75 solar panels (27kWh maximum energy production) and the 3 Tesla Powerwall batteries.
All heating is solar powered, delivered by underfloor heating – only required in colder months absence solar gain.
Mechanical Ventilation and Heat Recovery (MHVR) is something we are also employing for clients on some of our current planning applications and builds and we were able to view the Vent-Axia unit chosen by Nick and Saffy. The MHVR unit changes air throughout the building roughly every four hours, exchanging ‘old’ air whilst retaining up to 80% of the heat, heating the incoming air.
Rain-water harvesting (from roof space and guttering) is collected in a 6000 litre underground storage tank. The water is then filtered and fed back into domestic use. Hot water is provide by a 450 litre, highly insulated tank, reducing the energy required to heat the water by as much as 43%.
Smart-operating Velux windows open in reaction to extreme temperatures and also close when it rains.
Particularly topical for some of our clients in this time of Nutrient Neutrality is the private sewage treatment works employed. Sewage is treated by a double, in-tandem septic tank system – which alone would treat effluent sufficiently. Thereafter, however, a reedbed filtration pond (complete with Water Voles and Frogs) removes the remaining nutrients ‘standard’ septic tanks and public sewage treatment works are currently struggling with. An important technological solution for many of our clients.
We continue to engage with the CLA and other partners to ensure we are best able to support our clients, deploy the best technologies and offer the best service possible through Durrants Building Consultancy.
The friendly team at Durrants Building Consultancy are always happy to discuss your plans and help you get your project off the ground. There is more information about our services here, but please get in touch with our Building Consultancy team to find out more on 01379 646603.
* Thermal transmittance, also known as U-value, is the rate of transfer of heat through a structure (which can be a single material or a composite), divided by the difference in temperature across that structure. The units of measurement are W/m²K. The better-insulated a structure is, the lower the U-value will be.