23 Jan 2008

Are these no heat homes?

“We are building homes with no heating systems already.” That was the bold claim made to me by Andy Porter of SIPS@CLAYS at the Harrogate Homebuilding & Renovating show back in November.

“Well, if you are, I’d like to see one,” I replied.

And so it came to pass that on Wednesday of last week, I met up with Andy and he took me to see two of their newly completed homes, one near Beverley in Yorkshire and the other in Accrington, Lancs, both of them what I would call classic selfbuilds.

Both homes had been constructed with Kingspan Tek SIPS panels, 142mm thick, with a U value of 0.2. This is hardly surprising as this is the construction system that SIPS@CLAYS specialise in — they were one of the original Kingspan Tek project partners. One of the houses was double glazed, the other used imported Swedish triple glazing, and both had been fitted with mechanical ventilation with heat recovery (MVHR). Neither house had anything in the way of conventional space heating, but both had wood burning stoves and both had solar thermal panels on the roof.

And what were they like to live in? Had they been cold during our recent cold snaps? Were the residents togged up with woolly hats and scarves, regretting their decision to be so bold as to do away with space heating?

Joan Barker, the builder of the house near Beverley, was still in the process of finishing off the house. She and her husband had moved in about a week before my visit (when it was really cold) and she said that it had been a little chilly for the first two days right after the move, and she admitted to using a couple of 2kW convector heaters to get up to comfort. But since then, no extra heating at all: and the wood burner was only being lit in the evenings. I would have said that she was already one happy bunny, and felt vindicated by her decision to do away with radiators and/or underfloor heating.

In Accrington, David and Jane Hartley had been living in their home since the summer and had had longer to figure out how it was responding. They kept their multifuel Dunsley stove going throughout the winter months (using coal only at night to keep it going) and the MVHR system distributed the heat around the house quite effectively. The room temperatures varied between 14°C and 18°C — not warm by current central heating standards but they found it quite comfortable. Although the stove is located in the middle of the large central living area downstairs, they tended to spend much of their evenings in an upstairs lounge and they noticed that the temperatures were more even upstairs than downstairs, where two of the peripheral rooms were noticeably cooler than the main living area where the stove is. This may be an effect of the uneven distribution of heat via the MVHR ducting.

So have they done it? Are these no heat homes, or are they merely modern variations of houses that might have been built in Beverley and Accrington 100 years ago, heated by solid fuel fires? Are we simply using modern technology (fans and ducting) to shift heat around a house more effectively? These are all interesting questions which I am not sure I can provide a coherent answer to just yet. But in the absence of any genuine Passive Houses in the UK thus far, these SIPs homes stand out as being as close to the new paradigm as we are likely to get in the next few years (being super insulated, pretty airtight, and mechanically ventilated) and they do look to be providing comfortable living conditions with a minimal energy input, which is after all what this low energy thing is all about. I guess the success or failure of these schemes should ultimately be assessed by the size of their fuel bills and in neither instance had they been in occupation long enough to make a judgement on this.


  1. Do these houses have any particular schemes to increase their thermal masses? Obviously these are single houses but, otherwise, how would you compare them with the Hockerton or BedZED schemes?

  2. This is exactly the set up we plan for our new build. Interesting that the MHRV seems not to give an even distribution. Poor design of duct layout, or just an inherent problem with the system?
    Delivering warm air to the ceiling (which seems to be the standard) has always seemed to less than ideal. I wonder whether a better degree of comfort could be obtained with floor level delivery, as I understand is usual in Canada.

  3. Ed,

    SIPs houses are routinely classed as low mass, but in reality this may not be the case. The panels themselves are remarkably heavy and need craning in, so there must be a fair amount of mass involved. It would explain why Joan Barker's house took a couple of days to warm up - that's typical of high mass houses.

    As for the ducting issues, I would anticipate that heat is lost in the longer lengths of ducting, which would typically be going to the peripheral rooms on the ground floor, as the heat recovery units are conventionally sited in the loft or at the top of the house. This is where the Accrington one was. You can balance the airflow at the outlets and inlets but you can't do much about varying temperatures.

  4. How can one claim that a house is a No Heat House, if there is a solid fuel stove incorporated into the design?

    The MHRV should help distribute any heat generated by heat emmitting equipment in the house - computers, cookers, fridges etc, but MHRV cannot be 100% efficient. If the ambient external temperature is lower than the desired internal temperature, some form of heat source will be required.

  5. Do MHVR units have to be in the loft/roof? what about on the first floor then ducting to floor of ground floor would not be such a distance? Would seem to make sense to introduce warm fresh air at bottom of house where you are living.