ᐅ Insulated Older Building from 1921: Converting from Gas Heating
Created on: 8 Mar 2022 11:44
W
Winniefred
Hello dear forum members,
We have been thinking for a while about what to do with our heating system in the long term. Of course, I have already read a lot, but we still don’t have a clear decision.
- The house is a well-insulated old building from 1921, a single-family semi-detached house. Currently, it is heated exclusively with gas; the boiler dates from 2010, is serviced annually, and is working perfectly.
- There is a two-flue chimney; one flue is connected to the gas heating system, the other is free.
- We currently use just under 11,000 kWh of heating energy per year; electricity consumption is about 2,200 kWh/year.
- The roof is a hipped roof, facing east, south, and west, with no shading at all. To put it plainly, it gets full sun all day long.
- The house is fully basemented, and we have quite a lot of space in the cellar, which has a floor area of approximately 40 m² (430 ft²). It is a vaulted cellar with enough headroom to stand comfortably. Slightly damp, consistent with the building’s age.
- We do not have any underfloor heating anywhere. The radiators are modern, some installed as recently as 2017. The house has a timber frame construction, masonry walls, the roof is very well insulated (2017), the facade was well insulated in 1993, and the wooden beam ceilings are filled with slag. The windows are almost all well insulated from 2017, with only three still having double glazing from 1993.
We would like to avoid heating with fossil fuels. At the moment, I’m leaning toward a pellet boiler combined with solar thermal.
Does anyone have other ideas?
We have been thinking for a while about what to do with our heating system in the long term. Of course, I have already read a lot, but we still don’t have a clear decision.
- The house is a well-insulated old building from 1921, a single-family semi-detached house. Currently, it is heated exclusively with gas; the boiler dates from 2010, is serviced annually, and is working perfectly.
- There is a two-flue chimney; one flue is connected to the gas heating system, the other is free.
- We currently use just under 11,000 kWh of heating energy per year; electricity consumption is about 2,200 kWh/year.
- The roof is a hipped roof, facing east, south, and west, with no shading at all. To put it plainly, it gets full sun all day long.
- The house is fully basemented, and we have quite a lot of space in the cellar, which has a floor area of approximately 40 m² (430 ft²). It is a vaulted cellar with enough headroom to stand comfortably. Slightly damp, consistent with the building’s age.
- We do not have any underfloor heating anywhere. The radiators are modern, some installed as recently as 2017. The house has a timber frame construction, masonry walls, the roof is very well insulated (2017), the facade was well insulated in 1993, and the wooden beam ceilings are filled with slag. The windows are almost all well insulated from 2017, with only three still having double glazing from 1993.
We would like to avoid heating with fossil fuels. At the moment, I’m leaning toward a pellet boiler combined with solar thermal.
Does anyone have other ideas?
Benutzer200 schrieb:
It’s no different for the heat pump. You only need hot water anyway. With the heat pump, my cost is about 8 cents per day. So you produce hot water for €2.92 per year. Impressive. 😀
@OP: if the project already fails because of €300 (€200), or you don’t want to spend that, you might as well forget about it.
1993 and well insulated don’t really match for me.
What exactly is the wall structure?
Calculating the heating load and determining the flow temperature are the first steps…
It would also be helpful to know the total floor area, the heated floor area, and the room temperatures…
B
Benutzer2009 Mar 2022 08:38driver55 schrieb:
So you pay only €2.92 annually for hot water. Respect. 😀 No, it’s actually €29.20 😉
Thanks to the photovoltaic system, it works. Hot water is produced once a day with about 1 kWh.
So, a heat pump needs a supply temperature of around 75°C (167°F). Ideally, you should aim for less than 40°C (104°F) at an outside temperature of 0°C (32°F). In general, surface heating systems are more efficient: ceiling heating, wall heating, or underfloor heating. Since this is not feasible in an older building without major renovations, you can use type 33 radiators, which have a larger heat emission surface than type 22 radiators, for example. This allows you to lower the supply temperature, which saves costs. I am still researching this myself, so I can’t easily help you with your specific heating system. The first step would be to lower the supply temperature or adjust the heating curve. This also improves efficiency in gas heating systems. Then you can see whether the insulation is sufficient for a heat pump and whether you can reduce the supply temperature enough. However, this only works when it’s cold outside.
With your low gas consumption, this should actually be feasible.
Just as a side note: 11,000 kWh consumption. You still need to subtract the efficiency of the gas heating system. Let’s say around 10,000 kWh for a round figure. This amount of heat has to be generated by the heat pump. A heat pump produces more than one kWh of heat from one kWh of electricity. This is indicated by the COP (Coefficient of Performance). For new buildings, a COP of 4 or higher is targeted. With radiators, it’s usually closer to 3. So, 10,000 kWh / 3 = 3,333 kWh electricity. Depending on the electricity price, that means roughly 1,000 €/year for heating electricity. The COP depends on the flow temperature, which is why it is so important. You can use this for rough comparison calculations in your head. Sometimes the efficiency of an old heating system is only about 70%, but professionals should check that. In that case, the required heat output would also decrease.
Just as a side note: 11,000 kWh consumption. You still need to subtract the efficiency of the gas heating system. Let’s say around 10,000 kWh for a round figure. This amount of heat has to be generated by the heat pump. A heat pump produces more than one kWh of heat from one kWh of electricity. This is indicated by the COP (Coefficient of Performance). For new buildings, a COP of 4 or higher is targeted. With radiators, it’s usually closer to 3. So, 10,000 kWh / 3 = 3,333 kWh electricity. Depending on the electricity price, that means roughly 1,000 €/year for heating electricity. The COP depends on the flow temperature, which is why it is so important. You can use this for rough comparison calculations in your head. Sometimes the efficiency of an old heating system is only about 70%, but professionals should check that. In that case, the required heat output would also decrease.
Winniefred9 Mar 2022 16:49So, here is a summary:
1. Heating load calculation by the engineer
2. Check the supply temperature with the plumber
We have a 100m2 (1,076 sq ft) house (all 100m2 are heated, and there is nearly 40m2 (430 sq ft) in the basement which is unheated but could be heated). It is a detached house on three sides, and the mentioned gas consumption is just under 11,000 kWh with electricity usage around 2,200 kWh – these are good values, even if the supply temperature might be set too high. On the ground floor, we keep about 20°C (68°F), around 21°C (70°F) in the children’s rooms on the first floor, and approximately 22°C (72°F) in the bathroom there. In the attic (where only our bedroom is located), the temperature is about 18°C (64°F) in winter, and we barely use heating there. Only 2 of the 3 radiators upstairs are in operation, and they are set to level 1. We still need to insulate the ground floor slab, as there is potential for improvement. The basement ceiling is a vaulted ceiling with many pipes running through it, so insulation there is not practical. We planned to wait with insulating the ground floor slab until we know which heating system will be installed.
Wall construction: The previous owner never showed up to meet us; everything was handled through the real estate agent, so we don’t have detailed information. From the inside, I can say there is plaster, then masonry made of typical red bricks about 20cm (8 inches) thick as far as I can tell. Then there is insulation, which I measure at 21.5cm (8.5 inches) including the exterior plaster layer. However, I don’t know the exact type of insulation. The attic was newly insulated in 2017, with insulation between and below the rafters. I would need to check the thicknesses.
1. Heating load calculation by the engineer
2. Check the supply temperature with the plumber
We have a 100m2 (1,076 sq ft) house (all 100m2 are heated, and there is nearly 40m2 (430 sq ft) in the basement which is unheated but could be heated). It is a detached house on three sides, and the mentioned gas consumption is just under 11,000 kWh with electricity usage around 2,200 kWh – these are good values, even if the supply temperature might be set too high. On the ground floor, we keep about 20°C (68°F), around 21°C (70°F) in the children’s rooms on the first floor, and approximately 22°C (72°F) in the bathroom there. In the attic (where only our bedroom is located), the temperature is about 18°C (64°F) in winter, and we barely use heating there. Only 2 of the 3 radiators upstairs are in operation, and they are set to level 1. We still need to insulate the ground floor slab, as there is potential for improvement. The basement ceiling is a vaulted ceiling with many pipes running through it, so insulation there is not practical. We planned to wait with insulating the ground floor slab until we know which heating system will be installed.
Wall construction: The previous owner never showed up to meet us; everything was handled through the real estate agent, so we don’t have detailed information. From the inside, I can say there is plaster, then masonry made of typical red bricks about 20cm (8 inches) thick as far as I can tell. Then there is insulation, which I measure at 21.5cm (8.5 inches) including the exterior plaster layer. However, I don’t know the exact type of insulation. The attic was newly insulated in 2017, with insulation between and below the rafters. I would need to check the thicknesses.
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