energy

The challenge of space heating

It’s a lot easier to reduce electricity use than gas use. That’s something I’ve been mulling over during January and February as I try and reduce our overall carbon footprint. With electricity, the quick wins are better known – energy saving light bulbs, efficient appliances, only boiling what you need in the kettle and so on. And all of that will make little difference to your carbon footprint if you’re on a 100% renewable energy tariff anyway.

The bigger issue is heating, which for most of us in Britain is gas, used for both water and space heating. Here’s the breakdown, from a recent Climate Change Committee report on housing:

As a nation, 63% of household energy use goes to heating space. That’s because we have have shifted over the decades towards the comfort and convenience of central heating. The whole house is heated, even if the occupants are all in one room for the evening, watching television.

Part of heating Britain sustainably is going to be picking apart the idea of central heating. Not completely – nobody wants to go back to hearths and three-bar fires. But there are measures that that introduce more sophistication into the ‘one thermostat to rule them all’ default of older central heating systems. Thermostatic radiator controls allow users to turn individual radiators down or off. If you fit these, you can turn off the heating in a spare room and shut the door, for example.

That’s useful, but the way we use a house changes throughout the day, and most of us won’t be running around turning radiators on and off. That’s where smart heating controls can make a difference, creating heating zones that can be customised according to the time of day. We might warm the downstairs more during the day, and the upstairs more at night. For those with larger homes and rooms that aren’t used as much, that could make a big difference.

What are we doing ourselves? This year I’m trying to nudge our 1920s terraced house towards an A rating for efficiency, and over the last couple of months I’ve been thinking about heating. I’m creating a heating zone in the front room where we tend to be in the evening. I’ve just had it carpeted, somewhat reluctantly as I loved the wooden floor, to help keep prevent heat loss. I’ve re-hung some sliding doors to partition the front from the rest of the open-plan downstairs, and added thermal curtain linings.

I will at some point get smart heating controls, and there’s a bay window that would be much better with triple glazing. But that’s getting expensive, and I have to pay for external cladding first. There’s more wall than window, and it’s single brick. We’ll come to that later in the year.

Another possibility is infra-red heating, which warms the contents of a room rather than the air. I don’t have much experience of these, but they may work in a couple of places in our house to deliver heat in specific areas that we need it. Let me know if you’ve installed these at all, as I’d be interested to hear how they worked.

With better insulation, electric heat and smarter heat, we can reduce that big red slice of the household energy use, both for ourselves and collectively.

11 comments

  1. Hi Jeremy

    I installed the Hershel infrared heating panels in my previous house (once I had renovated the house with external insulation), and this was part of a complete refurb. It was a replacement for the old gas system boiler; and there was only heating downstairs, not upstairs. So the capital cost was similar to installing a new gas boiler and radiators. I installed the infrared panels in the ceiling as this is the best place for them and each panel was linked to its own control. I found this very effective and I liked the warming effect of the panels. It worked well because the house was small (approx. 70m2) and was well insulated.

    I am happy to talk more about this if you want additional advice

    Regards, Emma

    1. A good solution for some, especially in a new-build context or if you’re replacing a boiler. We already have an efficient boiler and are generating more electricity on site than we need, so I’m looking at electric heat and ways to cut down on gas use. If we needed a new boiler, I’d definitely consider replacing it with a mini-CHP unit.

      Not sure why this option is practically invisible in the UK when it is used succesfully in other parts of the world, but I suspect that if one of the bigger energy companies got behind it we could see them becoming more common.

  2. Baildon Methodist Church, Bradford uses for infrared space heating. It is very efficient. Apart from CO2 reductions,whole-life costs are better than gas because the gas system had to be serviced annually and the boiler replaced every 15 years.

    1. The problem with electricity used for heating is that it degrades high grade energy into heat, which is inherently thermodynamically inefficient.

      If the electricity was thermally generated, the situation is even worse because 60% of the chemical energy in the fuel will have been wasted in the cooling system.

  3. It would be useful to know what the typical space heating energy demand is by house type, so we can see how well (or not) we are doing. We too live in a solid brick wall terrace house (1901) with big bay windows, so the problems are similar.
    We have a four zone heating system – living room normally heated in the evening (which also has a wood burning stove), kitchen/breakfast room normally heated in the morning; upstairs bedrooms heated in the late evening and first thing in the morning, plus the bathroom heated whenever anywhere else is being heated. We have both TRVs and digital programmable thermostats. The thermostats are set to heat to 16degC and overridden for heat at other times of the day and for extra comfort as needed, with a drive to wear more clothes rather than just up the room temperature. The upstairs hardly ever comes on since enough heat leaks from downstairs and the roof and attic have been completely rebuilt with a huge amount of insulation and as air tight as possible.
    The kitchen/breakfast room is currently being upgraded to underfloor heating coupled with lots of insulation and airtightness, so will see how it goes next winter. A big problem here has been cold walls due to rising damp so they have been tanked as well as insulated. It would be good to get the space efficient enough to run an air-source heat pump for the underfloor heating instead of using gas.
    A big problem is the large north-facing bay window in the living room, which though upgraded with secondary glazing and reasonably air-tight, create such a down-draught off the cold glass – as well as cold solid walls – that the whole room becomes uncomfortable to sit in unless the temperature is quite high. The plan is to triple-glaze, insulate and improve airtightness to get rid of the draught and so make the room comfortable at a lower temperature.
    I have found over the years that managing draughts and cold surfaces is a big winner since we feel warmer even if the room temperature is lower.

  4. Interesting – you’ve clearly put a lot of thought into your heating, and that’s useful to learn from.

    Bay windows or French doors are a problem, with all that cold air rolling off the glass. The draught comes from warm air being drawn in behind the curtains at the top, cooling and then seeping out the bottom. In the old days they fitted valances to the top of the curtains to prevent this, and then dropped curtains all the way to the floor. Valances tend to be unfashionable now, but perhaps it’s time they were re-invented for the 21st century.

  5. Hi Jeremy,

    I suggest the easiest and cheapest way to reduce energy consumption from heating is to lower the thermostat. I once read (don’t have time to find a link now) that in 1960, the average room temperature in the UK in winter was 13 C.
    Clearly there are health/safety considerations to be made, but for most people this is not a problem.

    I suggest targeting heat more to the individual, and less to the room. Devices like these are great (I have no affiliation):
    https://reductionrevolution.com.au/products/heat-master-foot-warmer-mat-heater
    https://reductionrevolution.com.au/products/sunbeam-heated-cushion

    Cheers, Angus

  6. Yes, lowering the temperature is one immediate thing to do. We did that years ago, and the default is always to put a jumper on first!

    Good suggestions on the person warmers. There’s certainly a place for low wattage targeted heat.

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