Where does the heat go?
According to Harold Orr, who built the Saskatchewan Conservation House in the 1970s, which was the forerunner of the Passivhouse, when he and his team externally insulated a 1960s house and tested it 10% heat loss goes through the walls, 30-40% heat loss through air leakage, 10% through the ceiling, 10% through windows and doors and 30% through floors.( Henry,Mike, "Harold Orr's Superinsulated Retrofits," The Sustainable Home, August 9, 2013, thesustainablehome.net)
Reducing heat loss saves money, which as I write in 2022 with rapidly rising energy prices sounds attractive. However, where we start depends on may factors - do we own the property, where we think the greatest heat loss is, what is financially achievable. We need to spend money in order to save money, which if we don't have money is a catch. Here in Scotland Home Energy Scotland is a good place to go to get advice and grants to help. There are also some cheaper quick options which can be done in stages making them more accessible
Reducing heat loss saves money, which as I write in 2022 with rapidly rising energy prices sounds attractive. However, where we start depends on may factors - do we own the property, where we think the greatest heat loss is, what is financially achievable. We need to spend money in order to save money, which if we don't have money is a catch. Here in Scotland Home Energy Scotland is a good place to go to get advice and grants to help. There are also some cheaper quick options which can be done in stages making them more accessible
Air leakage (drafts)
When we had Gruinard thermally imaged and pressure tested one of the things that stood out was sir leakage. Our windows were about 8 years old, UPVC, seems to shut well but the ones on the weather side of the house leaked. This was due to the seals having degraded over time. Gruinard is sheltered on all sides by trees and is surrounded by houses so protected to some degree from the worst of the weather. One room had always been difficult to heat. When I bought some rubber stick on window seals from the local DIY shop and spend an hour (probably not even that) cleaning the UPVC and sticking it on, the room changed to one we could heat, if the radiator was on full. We needed to add thermal blinds and curtains to reduce the amount of heat needed, but it was a big start. We saw smaller changes in other rooms.
The original part of Gruinard was built in 1965, and as part of the building style at that time electric wires were run in metal conduit down from the ceiling. In the loft the wiring is still in conduit though many of the suction boxes have been opened to allow work to be done on the wiring. All the sockets that didn't have plugs in them leaked, Putting child socket protectors in the sockets affected solved the problem, without much expense.
The other place we lost a lot of heat was skirting boards. The internal walls are all block and plaster but the plaster only runs to just below the top of the skirting boards leaving a big gap leading done to the vented underfloor, allowing for significant air leakage. This can be solved by replastering down to the floor, making an airtight join - an expensive and messy job but the gold standard if you are doing a big renovation of a room. We aren't in the market for that at the moment so we sealed above the skirting boards and where the skirtings meet the floors with coloured wax. This seems to have improved things.
Holes in ceilings for wiring or plumbing and the same in floors can also allow arileakeage and significant heat loss. These can be closed with rubber bungs made for the job.
When sealing up gaps and reducing air leakage remember to maintain adequate ventilation especially if you have any form of combustion in the house such as a wood burning stove.
The original part of Gruinard was built in 1965, and as part of the building style at that time electric wires were run in metal conduit down from the ceiling. In the loft the wiring is still in conduit though many of the suction boxes have been opened to allow work to be done on the wiring. All the sockets that didn't have plugs in them leaked, Putting child socket protectors in the sockets affected solved the problem, without much expense.
The other place we lost a lot of heat was skirting boards. The internal walls are all block and plaster but the plaster only runs to just below the top of the skirting boards leaving a big gap leading done to the vented underfloor, allowing for significant air leakage. This can be solved by replastering down to the floor, making an airtight join - an expensive and messy job but the gold standard if you are doing a big renovation of a room. We aren't in the market for that at the moment so we sealed above the skirting boards and where the skirtings meet the floors with coloured wax. This seems to have improved things.
Holes in ceilings for wiring or plumbing and the same in floors can also allow arileakeage and significant heat loss. These can be closed with rubber bungs made for the job.
When sealing up gaps and reducing air leakage remember to maintain adequate ventilation especially if you have any form of combustion in the house such as a wood burning stove.
Insulation
Before looking at changing our heating system we needed to reduce our heat loss. When we first moved into our 1960's house it had the standard insulation of that era. The windows were double glazed but many years old, some made of aluminium. The boiler was gas but ageing and needing replaced. Our fuel usage in our first year was 130,000kWh according to our bills. The average UK household in 2007 used 18,000kWh of gas - www.berr.gov.uk/files/file43304.pdf - and according to the now defunct Energywatch website the average annual gas use in 2007 for a 5 bedroom house like ours was 34,500kWh. So we had a very long way to go. Driven intially by financial need we installed a more efficient boiler. At 70% efficiency we would not think of this as an efficient boiler now but it was then. We insulated our loft (200mm), put in cavity wall insulation, installed double glazinng, radiator shelves, new radiators with foil behind reducing our gas use to 42,500kWh in 2008. Not bad but could do better.
So how much insulation should we put in. Cavity wall insulation is straight forward, if you house is suitable then fill the cavity - what with. The options seem to be recycled newspaper - which I believe is very good and works well if you can find someone who is trained to install it - polystyrene balls or polystyrene foam. Usually, it is what your local installer is proficient in. But it is worth asking around. Make sure your cavity is suitable and you aren't putting your house at risk of damp - ask the experts.
Lofts are also supposedly easy. 300mm of insulation. Ah yes but 300mm of glass wool gives a very different insulation level to 300mm of foil backed expanded polystyene. The polystyrene is over twice as effective at insulation as the glass wool but is energy hungry in manufacture and chemical hungry as well. In lofts we can afford the space if it isn't floored but if is is floored then the options are to lift the boards and fill the space - often only 100 - 150mm. In this case some form of relective material as well might be worth considering.
Insulating floors depends on the make up of the floor. Concrete on earth need insulation above or the floor dug out and relaid - urgh. Chipboard or floor boards on beams, the voids between the beams may be filled with glass wool or polystyrene if it is accessible.
We have suspended wooden floors, over ventilated voids. They need something under them but if the boards are enclosed then condensation may arise leading to rotten timbers. My understanding is that natural fibres, like sheeps wool, can be used as they can buffer this condensation by absorbing and releasing it without changing their insulating properties. It does mean climbing down under the floors - in our case 20 - 40 cm depth and putting it in. We installed 200mm mineral wool predominantly held up by netting, some held up by breather membrane. We shall see which works best when we have the house thermally imaged.
So how much insulation should we put in. Cavity wall insulation is straight forward, if you house is suitable then fill the cavity - what with. The options seem to be recycled newspaper - which I believe is very good and works well if you can find someone who is trained to install it - polystyrene balls or polystyrene foam. Usually, it is what your local installer is proficient in. But it is worth asking around. Make sure your cavity is suitable and you aren't putting your house at risk of damp - ask the experts.
Lofts are also supposedly easy. 300mm of insulation. Ah yes but 300mm of glass wool gives a very different insulation level to 300mm of foil backed expanded polystyene. The polystyrene is over twice as effective at insulation as the glass wool but is energy hungry in manufacture and chemical hungry as well. In lofts we can afford the space if it isn't floored but if is is floored then the options are to lift the boards and fill the space - often only 100 - 150mm. In this case some form of relective material as well might be worth considering.
Insulating floors depends on the make up of the floor. Concrete on earth need insulation above or the floor dug out and relaid - urgh. Chipboard or floor boards on beams, the voids between the beams may be filled with glass wool or polystyrene if it is accessible.
We have suspended wooden floors, over ventilated voids. They need something under them but if the boards are enclosed then condensation may arise leading to rotten timbers. My understanding is that natural fibres, like sheeps wool, can be used as they can buffer this condensation by absorbing and releasing it without changing their insulating properties. It does mean climbing down under the floors - in our case 20 - 40 cm depth and putting it in. We installed 200mm mineral wool predominantly held up by netting, some held up by breather membrane. We shall see which works best when we have the house thermally imaged.
Heating
In 2009 we had our heating system repiped and insulated. We then installed a woodburning stove, which we used to brighten and warm the long cold dark days of the winter 2009 to 2010 - it started to snow on the 17th of December 2009 and there was snow on the ground continously until April 2010. Our gas usage for 2009 was 28,786kWh but that missed most of that cold spell. 2010 our heating use was 25,878kWh not as low as the UK average household but 10,000kWh lower than the average gas use of a house of similar size.
It then gets more complex because at the start of 2011 we installed a wood pellet boiler, which means that there is no metering of our use. However our calculations show we used 23,275kWh and in 2012 24,916kWh. Not sure why the increase in 2012 other than it was a grey miserable year.
It then gets more complex because at the start of 2011 we installed a wood pellet boiler, which means that there is no metering of our use. However our calculations show we used 23,275kWh and in 2012 24,916kWh. Not sure why the increase in 2012 other than it was a grey miserable year.
Cleaning and oiling slate - fireplace
This is a little bit of an aside but it is about maintaining what we have and not buying new. Our house has a Cumbrian Slate fireplace, green Honister Slate - www.honister-slate-mine.co.uk - from before the mine closed, it has now reopened. When we were getting our fireplace ready for the woodburning stove we needed to extend the hearth and so went to Honister to get the slate. It was a great day out, even for those of us who aren't keen on going underground. One big issue for me was how to clean slate and maintain it. Easy came the answer:
- clean with water, a little soap if need be
- allow to dry thoroughly
- then oil with olive oil - it doesn't smell.
It make a huge difference. Sadly, I don't have a photo of the first time I did it last year but the picture is of this year's reclean, quite a difference. It gives the slate a wonderful deep green colouring.
- clean with water, a little soap if need be
- allow to dry thoroughly
- then oil with olive oil - it doesn't smell.
It make a huge difference. Sadly, I don't have a photo of the first time I did it last year but the picture is of this year's reclean, quite a difference. It gives the slate a wonderful deep green colouring.
