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I live in a mid-terrace house (c1900) in the UK that faces east-west (roughly). The front door faces east; back door (opening into garden) faces west. There are no trees on our street. We have three stories and a typical side return.

The top floor has a small window (about .75m^2, but only half opens) on the east side, and a tinted Velux skylight (which opens) on the room on the west side. We have window coverings on all the large windows throughout the house.

The ground floor stays relatively cool. The first floor, where the bedroom is (east side) gets too warm for comfort during the day, and the top floor gets beastly. We have several ceiling fans and portable pedestal fans that help, but sometimes even the rooms are just too hot. Also opening the front and back door in the evening helps create a crossbreeze, but this mostly just affects the bottom floor.

Just opening the east-side windows in the evening helps, but not enough for the upper floors. Challenges are:

  • Air doesn't seem to move through the top floors; it stays hot up there.
  • We can't leave the bedroom window open at night, due to an anxious dog.
  • I have been told that an integrated loft fan would be difficult, expensive, and only modestly effective in this type of dwelling (due to it being difficult to place and the type of walls).
  • I am in principle against AC.

I have seen the following mentioned:

...but I'm unsure which, if any, of these will be effective in our case.

Do you have any advice for cooling the house? We're willing to consider both temporary and more permanent solutions.

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  • Have you asked your dog's vet about anxiety training? Commented Jun 30, 2023 at 18:18
  • On the dog question, some kind of grille or mesh to put across windows would prevent the dog escaping while allowing airflow. It wouldn't help if noise from outside was disturbing the dog. Commented Jun 30, 2023 at 20:39
  • Yes, the issue is noise. We've worked hard with the dog and he's improved (we use white noise generators, too) but he's quite not there yet. Commented Jul 1, 2023 at 12:49

2 Answers 2

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It seems that you have windows on the east side, but none on the west side? That would be the problem - you can't get cross flow at the upper floors where the heat naturally collects.

At a minimum, open the skylight on the 3rd floor on the west side and leave it open as much as you possibly can day and night. Maybe even work out a mount for a box fan or similar to blow air out through this skylight. It sounds to me like this is the highest opening in the house, so that should help release the hot air (which rises through natural convection), while the fan will boost the air flow leaving.

Consider simply putting a fan at the top of the stairs* on the top floor. This will help pull cooler air up the stairway adding to the natural convection movement that will happen. While it will pull the warmest air up into the upstairs, it should be helpful in moving cooler air up, too, and moving warmer air out, especially if it's assisted by a fan or two blowing out the window/skylight on this level.

Additionally continue to cover the windows, especially west facing ones to minimize solar heat gain from the West. Open east side windows, particularly on the lower floors to let cooler air in.


*Of course, only do this if there are no small children who might trip over the fan and tumble down the stairs. Also, you'd probably only want to do this when the house is naturally or artificially lit - i.e. move the fan away from the top of the stairs at night if someone might get up in the middle of the night and move up/down the stairs. OTOH, you'll probably be much cooler hanging out at A&E since they tend to keep that air conditioned in the summer...

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    A fan blowing out may be easier to mount in the top-floor east side window, even though it's small. Skylights can be awkward to deal with.
    – Ecnerwal
    Commented Jun 30, 2023 at 14:19
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You have several things going on:

  1. Solar gain: sun in the morning strikes the east windows, causing the rooms on the east side to warm. Similarly sun in the evening strikes the west windows. You want to block this heat from coming in.
  2. Hot air collecting in the upper levels and not escaping. This doesn't matter so much as to the orientation of the windows, although the solar gain from point 1 is a contributing factor. Once the heat is in, you want to get it out.
  3. Heat warming up things inside which stay warm into the evening. You want to pump this heat out too.
  4. Materials with a high 'decrement delay' or 'thermal mass' act as a time lag: they cool overnight and then release that cool during the day. For example masonry walls have a high value, while timber walls have a low value. A timber loft conversion has low thermal mass so tracks the outside temps with little delay, while a stone cathedral has a high thermal mass and the temperature changes little between day and night. Often we find the extreme temperatures uncomfortable and the average temps more pleasant (eg if it's 30C at midday and 10C at midnight both may be uncomfortable to be in, but a steady 20C might be fine), and so thermal mass makes things feel more pleasant overall.

For solar gain, it is more difficult to block insolation on the east-west axis than a south facing one, because at midday when the sun is in the south, it has a high angle in the summer which can be blocked with a brise soleil, but on the east-west axis the sun angle is low at sunrise/sunset and such a passive measure doesn't work.

Some of these African buildings have east/west windows with passive shading: here they tend to be built so outside the window is a vertical baffle on the south side, which shades the window from mid morning and mid afternoon sun when it is in the south east or south west respectively. That may not be feasible to fit externally depending on your architecture.

One thing you can do for solar gain is white- or foil-backed blinds or curtains, which are designed to reflect as much heat back out again. This does make a difference. Exterior shutters would do this better, but fitting them is not always practical. Partially reflective window films can help, but if installed on the inside bear in mind they will themselves heat up - again it's better if installed on the outside, but many are not weather resistant. They can also be very expensive, and fitting outside may not be feasible.

Having a similar situation to yours (east-facing windows only), white blinds helped more than window film, although I didn't go for the priciest kind of film.

The second point is about getting rid of the heat once it's in there. For this I've taken to opening two east-side windows and putting a stand fan between them, ie blowing air parallel to the windows. The fan sucks in air from one window and blows it out the second window. In the evening this makes a big difference: as soon as it becomes cooler outside than in, turning on the fan will flush out hot air trapped inside. I leave this running all evening to attempt to cool down the walls which have soaked up heat during the day.

When it's warmer outside than in, I don't think there is anything you can do short of keeping the windows closed and covered, making the best of the cool stored in masonry and other 'slow' materials. Eventually the heat will collect inside and you can vent it as above.

If it gets to the point where the outside temp is too hot and there is no more 'cool' to draw on inside, either you need to add thermal mass with more masonry or similar (not always feasible), or you need A/C to pump heat out. If the night time temps never fall to a comfortable level to recharge the thermal mass, only A/C will do.

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