ᐅ House (built in 2019) always too warm from April to October
Created on: 23 May 2023 07:28
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chewbacca123
Hello everyone, I wasn’t sure under which category to post this topic.
We have been living in our house for about four years now; it was built in 2019. The house is built into a slope, with the ground floor containing the living area, kitchen, workspace, and a small bathroom, and the basement level having the bedrooms, building services, and utility room. The attic is not converted.
Now that it’s slowly getting warmer, I notice again, as I do every year:
It’s so warm inside the house. The heating system, underfloor heating (heat pump), is no longer running. We have a thermometer in the cloakroom on the ground floor. This morning it showed 23.4°C (74°F), stuffy and uncomfortable.
Our house has a ventilation system (Wolf), a central ventilation unit. It runs at night and is supposed to bring fresh air into the house or extract air from the rooms as needed.
How can it be that we always have such heat? 23.4°C (74°F) in the hallway?
Of course, I should mention that we get a lot of sun. On the ground floor, in the living area, there are large south-facing windows which we shade when the sun is shining.
In the basement, the terrace door is 2m (6.6 ft) wide and also exposed to the sun. We shade that partially.
We installed the ventilation system back then because it was said to save us from having to open all the windows every morning. Now, between April and October, I basically spend my mornings opening all the windows anyway to get rid of the stuffy and unpleasant warmth inside the house.
Does anyone have similar experiences? How can it be that after a night with 12°C (54°F) outside temperature, the hallway is 23.4°C (74°F) at 7 a.m.?
When I leave the bedroom and walk up the stairs to the ground floor, I can feel the temperature rising with every step :-/
Could this be related to the building services system? The house was built in 2019, with 36cm (14 inch) Porit bricks.
Thanks for your help, best regards
ina
We have been living in our house for about four years now; it was built in 2019. The house is built into a slope, with the ground floor containing the living area, kitchen, workspace, and a small bathroom, and the basement level having the bedrooms, building services, and utility room. The attic is not converted.
Now that it’s slowly getting warmer, I notice again, as I do every year:
It’s so warm inside the house. The heating system, underfloor heating (heat pump), is no longer running. We have a thermometer in the cloakroom on the ground floor. This morning it showed 23.4°C (74°F), stuffy and uncomfortable.
Our house has a ventilation system (Wolf), a central ventilation unit. It runs at night and is supposed to bring fresh air into the house or extract air from the rooms as needed.
How can it be that we always have such heat? 23.4°C (74°F) in the hallway?
Of course, I should mention that we get a lot of sun. On the ground floor, in the living area, there are large south-facing windows which we shade when the sun is shining.
In the basement, the terrace door is 2m (6.6 ft) wide and also exposed to the sun. We shade that partially.
We installed the ventilation system back then because it was said to save us from having to open all the windows every morning. Now, between April and October, I basically spend my mornings opening all the windows anyway to get rid of the stuffy and unpleasant warmth inside the house.
Does anyone have similar experiences? How can it be that after a night with 12°C (54°F) outside temperature, the hallway is 23.4°C (74°F) at 7 a.m.?
When I leave the bedroom and walk up the stairs to the ground floor, I can feel the temperature rising with every step :-/
Could this be related to the building services system? The house was built in 2019, with 36cm (14 inch) Porit bricks.
Thanks for your help, best regards
ina
R
RotorMotor23 May 2023 14:13chewbacca123 schrieb:
When we run the mechanical ventilation with heat recovery continuously during the summer, the house gets very warm. We have already checked everything. It brings warm air into the house. kati1337 schrieb:
I had the same feeling with our mechanical ventilation with heat recovery back then. We also ran it during the day in summer at the lowest setting and raised it at night. It is very unlikely that a central mechanical ventilation system with heat recovery causes overheating inside the house.
Here’s a calculation to illustrate:
With active heat recovery, the temperature difference is usually only one or two degrees Celsius.
For example, yesterday we had 27°C (81°F) outside and 22°C (72°F) inside, resulting in a fresh air temperature of 23°C (73°F).
That’s only a 1°C (2°F) difference and about 50 watts of “heating power,” which is negligible.
If the heat recovery were turned off, the temperature difference would be around 5°C (9°F), equating to about 260 watts.
Even that wouldn’t make the house feel very warm, considering that a person already generates around 100 watts or a TV, computer, oven, etc. each produce several times more power.
By the way, shading on the inside barely helps because most of the heat is already inside at that point.
Also, shading east and west windows usually makes more difference than shading south-facing ones, as in summer the sun is so high on the south side that it rarely shines directly into the windows.
chewbacca12323 May 2023 18:01RotorMotor schrieb:
It is very unlikely that a central mechanical ventilation system with heat recovery causes overheating in the house.
Here’s a calculation:
With active heat recovery, the temperature difference is at most one or two degrees.
For example, yesterday we had 27°C (81°F) outside and 22°C (72°F) inside, and the fresh air temperature was 23°C (73°F).
So a 1-degree difference, which corresponds to about 50W of "heating power." That is completely negligible.
With heat recovery turned off, the difference would be 5 degrees, so about 260W.
Even that doesn’t make the house too warm, considering that a person already emits around 100W, and devices like a TV, computer, or oven quickly produce much more power.
By the way, interior shading does almost nothing. At that point, most of the heat is already inside.
Also, shading east and west windows is usually more effective than shading south-facing windows, because in summer the sun is so high on the south side that very little sunlight enters through the windows! I’m not saying that mechanical ventilation is the cause of overheating. However, it definitely contributes when daytime temperatures are above 25°C (77°F) in the shade and the system is running.
I recorded and analyzed this statistically for weeks during the last hot summer.
Of course, the heat in the house mainly comes through the large floor-to-ceiling windows and the patio door. Exterior blinds (like venetian blinds) in those areas would have been the solution. It’s a pity we didn’t consider that during the build. :-(
chewbacca12323 May 2023 18:06ypg schrieb:
I find this quite unusual. Like others who provide figures, they say a mechanical ventilation system with heat recovery alone won’t really be able to heat your house.
Yes, it is true that once the heat is inside, it’s hard to get it out. For example, we had to sign a waiver—though I don’t know the exact conditions—agreeing to forgo thermal insulation if we chose not to install shutters on the south side. This was explained to us by the architect.
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I skimmed through your posts, including your first ones. You’ve been dealing with managing heat for quite some time now.
When the sun moves around and basically shines through the windows, the inside starts to warm up, especially with 10 or 12 sqm (108 or 129 sq ft) of windows that you don’t always want to keep closed.
Personally, I like the warmth inside the house. However, it could also be overwhelming depending on the amount of heat. I’ve noticed that the upper floor seems to get more heat despite having fewer windows than the open-plan living area on the ground floor. I’ve always attributed this to smaller rooms on the south side, as well as the tree canopy in our garden, which provides shade—this naturally also affects the south-facing side of our house.
Perhaps adding a heat-reflective film on your windows might help a bit? Have you considered planting one or two standard trees? The canopy doesn’t have to be dense—just enough to provide some shade to the upper floor. Unfortunately, we were not advised on this by the architect or the window installer; they simply presented shutters to us, and we went with those. We never saw Venetian blinds, which is a pity. There were just so many items to consider during construction that we didn’t have this on our radar.
We have our garden terrace directly below the large windows of the living area in the basement, which is covered with glass panels and an under-glass awning. So, there is still an opportunity to plant something there; some trees are already present in some form. We’ve also planted a few, but it will probably take about ten years before they provide any shade.
I think when the balcony window, which is one of the three large south-facing glass sections, is covered later this year or next, it will improve the situation somewhat. We won’t be using glass panels for this cover, but wood instead—dark and solid, blocking the sun completely, so the window can remain unobstructed at all times.
chewbacca12323 May 2023 18:08chewbacca12323 May 2023 18:17hanse987 schrieb:
When do your roller shutters go down? At the very first ray of sunshine or only after some time?No, they are programmed by me according to the position of the sun.
chewbacca123 schrieb:
Unfortunately, we were not advised properly by either the architect or the window installer; they simply presented us with roller shutters, and we went with them. Roller shutters are sufficient for the architect as thermal insulation…
chewbacca123 schrieb:
We never saw any Venetian blinds, which is a pity. There were just so many points on the checklist during construction that we didn’t consider it ourselves. Well, they do cost more. And back then, you probably didn’t take into account that roller shutters are usually either fully closed or fully open.
chewbacca123 schrieb:
That’s why you can still plant something here; there are already trees in some form. Yes, it’s not about planting a shade tree directly in front of the patio door, but I would consider how tall a nice tree would need to be in your situation to provide some relief.
For example, this tree in our garden stands about 4.5 to 5.0 meters (15 to 16.5 feet) from the house and its canopy provides shade on the patio, and thus inside the house, starting at the end of April. Okay, that’s on the ground floor… I wouldn’t underestimate plants. Most people here who want a low-maintenance garden don’t consider the sound and solar protection offered by foliage. Not to mention the charm a tree adds to a garden.
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