Eco House Design Built to Passive House Standards in Lumsdaine

This project is a net exporter of renewable energy and is built to Passive House levels of super insulation, triple glazing, air-tightness, passive solar gain and thermal mass, with the benefit of a fully integrated solar thermal hot water & photovoltaic panel roof array. Heating is via wood-burning masonry storage heater. Mechanical heat recovery ventilation system guarantees pre warmed clean fresh air and a wind turbine fully powers the owners all electrical car. A Polly tunnel and Permaculture garden allows for most of the home vegetable produce to be grown on site.

It works! After much private research on passivhaus and similar eco-build technologies we commissioned a specialist architect, Andrew Yeats of Ecoarc, to design us an eco-house for self-managed build. During the one site visit he made before the design on a cold February day as the wind howled over the snow off the North Sea, my thoughts turned naturally to heating. “We are thinking of having a ground-sourced heat pump with underfloor heating” I proffered. Andrew stopped, turned to me and said ”Why do you think you need a heating system”? That was the point I realised this was for real. Andrew introduced me to ‘eco-minimalism’ – just get the physics right and avoid the complex, expensive eco-bling!

My wife and I have now lived in the completed Wyndmyln House for over three years, we are fossil fuel free, running both house and (electric) car on sun and wind. I can now have fun with visitors who on entering often say “It’s lovely and warm, how do you heat the house”? to which I reply “That is the wrong question, the correct question is ‘How do you stop losing heat’”. The answer to the correct question is threefold; massive insulation all round; airtight construction with heat-exchange ventilation (not easy with masonry construction) and, (the bit timber frame houses miss), lots of internal thermal capacity. There are also numerous other refinements in this eco-design but those three are the essence.

Our 2.5kW wind turbine and 3kW of photo-voltaic panels generate some 7,000 kW hrs of power, much of which we use, and we import from Good Energy some 5,000 in the year. This runs the house and some 10,000 miles of car travel (with occasional free charging away from base). We have recently installed an ‘Island Grid’ so the house now runs off batteries and we will use more of our generated power and import less. There is a 3 sq.m. solar tube array for hot water and crucially, a South-facing, lean-to, double-glazed conservatory – our main heater. Even in February on a sunny day it gets up to 30c and then heats the house through high-level windows and a door. So we only need backup heating in December and January when the sun is low and, depending on the weather, part of November and February. Our backup is a large masonry stove, essentially a wood-burning storage heater. A Finnish design built by Stovemasons, it is the original ‘central heating’ literally in the centre of the house straddling the main living space and lounge. A load of 15kg hardwood logs, burnt at full ventilation, runs through a complex maze of channels dumping heat into the fabric. After a 4 hour burn it releases heat slowly for 24 hours. A ton of logs does the Winter which we supplement with small-wood and kindling from our own willow coppice. So the SAP rating of ‘A’ scoring over 100 for both energy and carbon is about right.

Lumsdaine Passive House
3kW of photo-voltaic panels
passive house architects

As for the rest of the permaculture garden, there is a large area of indigenous tree and shrub planting, a wildflower meadow with beehives and chickens, a polytunnel, soft and top-fruit coming up and a vegetable patch. It has been amazing to see a huge variety of wildlife move in as we transformed a field of ryegrass into a concentrated jigsaw of micro-habitats. Being surrounded by an organic farm helps the wildlife along.

In a house like this we are cosy and low-cost. We feel connected to nature, the weather forecast is now more important than the news. Will the rain re-fill our water barrels and top-up the wildlife ponds? Is there enough sunshine to avoid lighting a fire? Will the wind re-charge the car? As for aesthetics, it blends well with traditional rural Borders architecture; more ‘Plain Jane’ than supermodel. After all, how many times do you need to say ‘Wow!’ at the sight of your own home, it is for living in, it works!

For more images and video tour of the house please go to http://www.coldingham.info/wyndmyln/

Words & Pictures Richard Bond: