This week we popped in to one of the homes that we retrofitted in 2010/11 as part of a Government-funded project, Retrofit for the Future, to find out how it was performing.
The headline finding is that the house is now using 9% of the energy it previously used for space and water heating; down from 12493kWh to 1133kWh. Overall energy use has been reduced by 75%, with the carbon emissions from the remaining use offset by a cost-effective investment in off-site renewables.
We visited after one year and found that actual energy use was 47% less than that predicted by SAP. There has been a further significant fall since then. Over the intervening years, the average energy use has been 30% of the use originally predicted for space and water heating, ventilation and lighting; and total average use has been 50% of use in that first year.
We expect heat usage to remain steady at this lower level (for the current occupancy patterns) as the fall can be attributed to one-off factors in that first year:
the building was drying out
the thermal mass had no heat stored as the build completed in early autumn
the winter of 2010/11 was particularly cold
Use of energy for appliances and cooking remains the largest influence on energy use, forming two-thirds of annual use on average. As highlighted in previous posts this is very dependent on working patterns and the number of residents. The final 3% of energy use is by the metering system itself – with metering on 8 rings in the house to enable this analysis.
Last, but certainly not least, was the residents’ feedback. The most notable problem was a rain sensor on the automated Velux windows in the sunspace, but that has been repaired quickly enough, and the occupants continue to enjoy the comfort of their old but cheaper-to-heat home.
Earlier this year we heard Helena’s reflections on 20 years at Hockerton Housing Project. Now we hear from our newest neighbours, Deb and Pete, 2 years after moving from the local market town of Southwell…
“My husband and I moved in to Hockerton Housing Project just over two years ago. We are in our early to mid fifties and have a son of 27 years of age, who at the time was living in Japan but since then has come home to HHP which he loves!
We had lived in an ordinary house in Southwell for over 25 years and it was a big move for us albeit only a distance of 2 miles.
Why did we make the move? We knew we loved growing things, in fact we had an allotment in Southwell for a long time; we knew we wanted to have farm animals but didn’t want to be tied down by them or for that matter the growing; and we knew we wanted to live as sustainable a life as possible!
But we were worried about the unknowns of cohousing – the amount of work we would have to do in the community, privacy, and how we would fit in.
Two years on we wonder what on earth we were worried about.
It is great to have sheep, that I look after (by choice) on a day to day basis, but someone else is always around to look after them when I want to go away for the weekend or on holiday. It is the same with the people who look after the chickens, they just tell us when they are going away and someone volunteers to look after them until they are back.
As for the growing – it is a 1/5th of the work of looking after your own allotment and so much more satisfying than seeing food wasted when there is a glut of something. I have a well-used jam and chutney pan and a fully-stocked freezer to see us through the winter for fruit and veg. Our bees produce our own honey which tastes simply wonderful…in fact it’s a strong favourite with the extended family and hence I managed to get through 12 jars last year!
I have learnt from others to deal with the ewes lambing, there is always someone else about to help out when intervention is needed, and sharing the lambing experience is just awesome. We had 16 lambs this year, 8 boys and 8 girls so have a flock of 32 altogether. Amy, my next door neighbour who is ten is going to be a fab little shepherdess…next year I could almost leave the lambing to her!
No longer do I get in my car and go miles to purchase flowers for my little flower business instead I walk out into my garden or up to the cutting garden at the allotment to select seasonal sustainable flowers which smell gorgeous. That was something I never dreamed of doing until I moved here. I nip into our cooperative’s office a couple of times a week to check the inbox and promote and manage tours – it’s a twenty five yard walk from my back gate. I guide tours when we have them for schools and universities with other residents and also do catering for conferences when they are held in our purpose built sustainable venue.
In terms of privacy, my life is more private here than it ever was in the middle of Southwell. As residents there is a great respect for each others’ privacy but this all happens without being made explicit.
This is actually how I hoped life would be, it is idyllic. You do have to pinch yourself every day when you turn round that corner at the end of the road you come into another world. So many local people come and say I never knew that this was here and are blown away by its beauty and how warm our homes with no heating really are!”
If you want to find out more, do come and see for yourself on our next public tour on 19 September – booking essential!
Have we ever mentioned how thermal mass keeps our homes warm in winter and cool in winter?
No doubt if you have visited us you’ve heard the stats and felt the benefit, but a day like today makes the benefits all the more evident.
The thermal comfort of our homes is met through the application of three key design principles:
Thermal mass to store heat in the summer months to keep the home cool in summer and warm in winter
Passive solar gain to reduce the need for space heating and artificial lighting
Super-insulation and buffer zones to provide a reduced temperature gradient between the inside and outside of homes.
So on a day like today we shut the triple-glazing between the living space and buffer zones, along with curtains and shutters if we are out and about, to keep out warm air and solar gain; and let the thermal mass soak up the heat when we are around the house. We have built passive ventilation into our buffer zones – otherwise known as skylights in the conservatory and porch area – which are vital to keeping the temperatures in those spaces comfortable.
Given the warnings yesterday from the Committee on Climate Change, we think cooling, or overheating, is an issue that needs addressing as part of the government’s home energy strategy. It should not be an add-on as there can be a conflict between approaches that keep heat in during winter and keep it out over summer.
The positioning of insulation in a construction element was completely disregarded by SAP up to and including SAP2005, and continues to be ignored by RdSAP. But it is essential if you want to get the heat storage benefits of thermal mass throughout the year for cooling, heat storage & release. Our walls, floor and roof could have the insulation placed on the inside, which would give exactly the same U-Values and hence RdSAP result, but completely different and appalling thermal performance of the house as a whole in warmer weather. Instead of being absorbed into the thermal mass, the passive solar gain would continue to raise the temperature until vented in some way.
Even though this is beginning to be recorded by SAP, RdSAP does still not differentiate between internal and external solid wall insulation. Neither assessment reflects the benefits in their overall assessment of thermal comfort. If the Government wants to prepare homes for the 21st century, and beyond, these tools will need to both recognise and reward the way external insulation can“lock in” the mass of the walls to deliver summer cooling and winter heating.
One of our longest-standing residents reflects on her time at HHP….
This is the 20th year since we joined HHP. We had recently returned from volunteering in Namibia and felt that sustainable development needed to start in the affluent West. We had relocated to Nottingham as I had a medical job there and Simon was looking after our small son Luke and looking for some way of using his engineering skills and doing it sustainably. By chance he came across HHP who were looking for a family to join them and the rest is history!
In those days (1995) I think we were more about sustainable and autonomous housing and climate change was not such an obvious issue but of course that has all changed and Simon now spends a great deal of time thinking about Renewables although our core business of demonstrating and promoting zero energy and sustainable housing continues and has lost none of its relevance today.
We moved into our brand new house in February 1998 after 18 months in a caravan with by then 3 small children. Simon had contributed to the self-build and being on site allowed him to juggle the family and building whilst I went off to a warm comfortable hospital every day! Our neighbours at the time were in a similar position which allowed some complementary childcare and a lot of mutual support!
Over the 20 years the Project has grown in so many ways. We had not realised the amount of interest it would generate with about 30,000 visitors, a significant amount of media interest and a small business that has continued to promote sustainability and provide employment for some of the residents.
Families have come and gone and we are now the last original family. Our children are grown up and Flo who was born when we were in the caravan is doing A levels and considering her future. It is perhaps not surprising that Luke is studying permaculture and small-scale organic horticulture in Leeds and Naomi is down in Falmouth studying Environmental Science. Their childhood in this wonderful site has been spent in the woodland and lake, in a small community of children and adults where they have had the freedom to explore and learn in safety. Parenting them has been easy. It is a pleasure to see other small children growing up and enjoying this space that we have helped to create.
As old families have moved on it is sad to lose that collective memory of the first days and the struggle to get planning permission and the houses built. We will be the last to remember why we did things this way or that and why that particular phrase in the secondary rules was written that way. But new families have brought in fresh energy and ideas and keep the direction of the business gently changing depending on interest, skills and available time.
Simon and I have no plans to leave and this lifestyle and place is perfect for us. The apple trees are in blossom and the new plants in the polytunnel are thriving and ready to go out. As the spring sun floods the conservatory after earlier rain, I am as excited as ever to throw open the doors to the bedrooms and know that the temperature in the house will stay in the low 20s until November.
After 20 years here our lives will change as the children leave and we have a bit more time for ourselves. More time to spend on the land, more time to sort out 20 years of childhood paraphernalia and more time to sit in the kitchen, conservatory, garden or lakeside depending on the weather and the season just enjoying this extraordinary place we helped to create!
Hockerton Housing Project is featured in a new book, The ‘One Planet’ Life: A Blueprint for Low Impact Development. The guidebook has been written ‘for everyone on the path towards a way of life in which we don’t act as if we had more than one planet Earth. The book also represents a manifesto for a change in attitude towards land use’.
You can get a taster in this informative blog about our development by the author David Thorpe, who is also a founder and core group member of the One Planet Council, and former director of publications at CAT.
If you want to see it for yourself, come on our next tour.