Now that we’ve lived in our 1950’s 3 bed detached house for one year, much thought has gone into deciding what changes we’d like to make.
The “eco” wish-list includes:
• A generous porch on the front to minimise heat loss when entering/leaving the house.
• A utility room by the back door to create the same draught-lobby effect there.
• Super-insulate the loft conversion, the solid walls (externally) and the ground floor.
• Replace the single glazed windows with high quality timber framed windows (hopefully achieving a whole window u value <1, preferably 0.75)
• Ensure air tightness of 3m3/m2 at 50 pa pressure, or less than 1m3/m2 if possible
• Install a mechanical ventilation system with heat recovery (MVHR)
• Replace the ailing gas boiler with suitable means of space and water heating
• Installing low-flow devices to reduce water use
• Possibly add PV panels on the south-facing roof
In other words, we will apply to our house some of the principles which form the basis of the Passivhaus approach to building ultra-low energy homes.
The Passive House standard is for new buildings, but there is another standard which is specifically for existing buildings. This is the EnerPHit standard for Passive House retrofit. Houses built to this standard will use about 80-85% less heat and power than the average home.
This is the standard that we are aiming towards – although we don’t know yet just how close we might be able to get. To see a relatively recent description of this standard (a draft document), go to http://www.passiv.de/01_dph/Bestand/EnerPHit/EnerPHit_Criteria_Residential_EN.pdf
The really difficult question is “How far does it make sense to go, and what is within our budget?
Thursday, 24 February 2011
Gas, Electricity and Water use in Year 1
We now have over 12 months of gas, electricity and water readings, taken on the same day every month so we can compare seasonal variations.
During the first winter (in Feb 2010), the gas boiler broke down for 2 weeks. This reduced the gas bill a little, but increased the electricity bill significantly as we brought in one electric heater so we could at least keep one room warm.
In a house like ours with an Energy Performance Certificate (EPC) rating of E and no eco-features at all, you might expect our annual gas, electric and water use to look something like this:
EPC/SAP estimated gas use - 32700 kWh
Average UK electricity use - 3500 kWh
Average UK water use - 140-150 litres per person per day
However, our actual use in 2010 was this:
Year 1 gas use - 21315 kWh
Year 1 electricity use - 1927 kWh
Year 1 water use - 94.5 cubic metres = 94,500 litres, or 64 litres per person per day
What this means is that we've reduced our bills significantly through being careful not to waste energy or water. In other words, we've done the "free" stuff. If we want to reduce energy and water use further we'll need to spend some money.
That said, I'm quite surprised how big the difference is between our actual use and the "UK average".
Our gas use is about 35% less than average for this kind of house as suggested by the Energy Performance Certificate (SAP calculation).
Our electricity and water use are approximately half of the UK average.
That's a lot of money and CO2 we're saving every year before we even start to make home improvements.
During the first winter (in Feb 2010), the gas boiler broke down for 2 weeks. This reduced the gas bill a little, but increased the electricity bill significantly as we brought in one electric heater so we could at least keep one room warm.
In a house like ours with an Energy Performance Certificate (EPC) rating of E and no eco-features at all, you might expect our annual gas, electric and water use to look something like this:
EPC/SAP estimated gas use - 32700 kWh
Average UK electricity use - 3500 kWh
Average UK water use - 140-150 litres per person per day
However, our actual use in 2010 was this:
Year 1 gas use - 21315 kWh
Year 1 electricity use - 1927 kWh
Year 1 water use - 94.5 cubic metres = 94,500 litres, or 64 litres per person per day
What this means is that we've reduced our bills significantly through being careful not to waste energy or water. In other words, we've done the "free" stuff. If we want to reduce energy and water use further we'll need to spend some money.
That said, I'm quite surprised how big the difference is between our actual use and the "UK average".
Our gas use is about 35% less than average for this kind of house as suggested by the Energy Performance Certificate (SAP calculation).
Our electricity and water use are approximately half of the UK average.
That's a lot of money and CO2 we're saving every year before we even start to make home improvements.
What's it like in its original state?
…and why would we wish to change it?
From June to August, it’s lovely if the weather is warm – quite cool inside generally. However, the west-facing rooms get really hot in the afternoon and the sun shines in our eyes.
In September, there’s a definite chill in the air – and not just outside. By the second half of September, the heating is very definitely on, and I start the morning ritual of wiping the windows from top to bottom and mopping up the puddles of water on the windowsill. Later in the day the condensation is back and I have to wipe it up again. If the weather is wet, we have laundry racks up in the lounge or dining room, and it takes over 24 hours to dry – which makes the condensation problem even worse.
Most of the wooden window frames have swollen over the last 59 years and can’t easily be opened or shut - to keep the heat in the windows are often closed anyway. The atmosphere is stuffy and uncomfortable and I dream every day of having a mechanical ventilation system with heat recovery bringing warmed fresh air in and taking away the stale damp air.
In October, I notice that the wooden window frames and the wallpaper around the window in the west-facing bedroom are gaining a growing patch of mouldy dots. The bathroom window frame (also west facing) is dreadful. I find drying the windows 3 or 4 times a day (to stop the condensation from pooling on the windowsill) is time-consuming enough without cleaning the frames and walls on a regular basis.
Last winter, shortly after moving in, we discovered that all the duvets stored in one wardrobe were wet from condensation running down the wall.
By late November it is cold and snowy – the coldest November for many years. It is harder than ever to get any part of the house to the right temperature. The hall always feels cold even when the lounge or dining room are too hot. And the kitchen only warms up properly if we are cooking. I’m forever adding and removing jumpers but never quite feeling comfortable. If we leave the doors open, cold air from the hall makes a warm room feel draughty. Once the heating goes off the temperature quickly drops.
December was also the coldest for many years. So far the boiler is holding out. Last winter it was out of action for 2 weeks (not an experience I wish to repeat), but apart from the occasional morning when we have to go out to the outhouse to get it going manually, all is going well so far. In fact, it has been so cold that the boiler runs constantly day and night, overriding the thermostat in the house. (This must be a feature that protects the boiler from extreme cold weather). Some rooms get too hot, and even the hall starts to feel almost comfortable, but it’s going to increase the gas bills this year.
These boilers in outhouses don’t seem very suitable for this kind of cold weather. What do people on low incomes do? Allow the heating system to override the thermostat and stay on to protect itself, running up a huge bill? Or switch it off altogether, live without heating and hot water, and pay for all the pipework to be mended when everything thaws?
January and February were slightly less cold than November and December this year, but the warm, dry weather in March and April came as a welcome change. A sunny spring afternoon makes the west-facing rooms nice and warm. Being able to hang the laundry to dry outside makes a big difference to humidity levels in the house, which of course reduces the need for heating too.
In May (and June), the heating is supposedly off, but if I get too cold it goes on again for a while. And the condensation on the windows is still present, but disperses during the morning (I refuse to wipe them dry – it seems as if I spent half the winter doing that).
From June to August, it’s lovely if the weather is warm – quite cool inside generally. However, the west-facing rooms get really hot in the afternoon and the sun shines in our eyes.
In September, there’s a definite chill in the air – and not just outside. By the second half of September, the heating is very definitely on, and I start the morning ritual of wiping the windows from top to bottom and mopping up the puddles of water on the windowsill. Later in the day the condensation is back and I have to wipe it up again. If the weather is wet, we have laundry racks up in the lounge or dining room, and it takes over 24 hours to dry – which makes the condensation problem even worse.
Most of the wooden window frames have swollen over the last 59 years and can’t easily be opened or shut - to keep the heat in the windows are often closed anyway. The atmosphere is stuffy and uncomfortable and I dream every day of having a mechanical ventilation system with heat recovery bringing warmed fresh air in and taking away the stale damp air.
In October, I notice that the wooden window frames and the wallpaper around the window in the west-facing bedroom are gaining a growing patch of mouldy dots. The bathroom window frame (also west facing) is dreadful. I find drying the windows 3 or 4 times a day (to stop the condensation from pooling on the windowsill) is time-consuming enough without cleaning the frames and walls on a regular basis.
Last winter, shortly after moving in, we discovered that all the duvets stored in one wardrobe were wet from condensation running down the wall.
By late November it is cold and snowy – the coldest November for many years. It is harder than ever to get any part of the house to the right temperature. The hall always feels cold even when the lounge or dining room are too hot. And the kitchen only warms up properly if we are cooking. I’m forever adding and removing jumpers but never quite feeling comfortable. If we leave the doors open, cold air from the hall makes a warm room feel draughty. Once the heating goes off the temperature quickly drops.
December was also the coldest for many years. So far the boiler is holding out. Last winter it was out of action for 2 weeks (not an experience I wish to repeat), but apart from the occasional morning when we have to go out to the outhouse to get it going manually, all is going well so far. In fact, it has been so cold that the boiler runs constantly day and night, overriding the thermostat in the house. (This must be a feature that protects the boiler from extreme cold weather). Some rooms get too hot, and even the hall starts to feel almost comfortable, but it’s going to increase the gas bills this year.
These boilers in outhouses don’t seem very suitable for this kind of cold weather. What do people on low incomes do? Allow the heating system to override the thermostat and stay on to protect itself, running up a huge bill? Or switch it off altogether, live without heating and hot water, and pay for all the pipework to be mended when everything thaws?
January and February were slightly less cold than November and December this year, but the warm, dry weather in March and April came as a welcome change. A sunny spring afternoon makes the west-facing rooms nice and warm. Being able to hang the laundry to dry outside makes a big difference to humidity levels in the house, which of course reduces the need for heating too.
In May (and June), the heating is supposedly off, but if I get too cold it goes on again for a while. And the condensation on the windows is still present, but disperses during the morning (I refuse to wipe them dry – it seems as if I spent half the winter doing that).
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