# House gets too Hot at night



## furthermore

Hello there,
I moved into my house 2 years ago, it's a 2 story house built in 1921. It was freshly insulated and had new windows put in about 2 years before I bought it. I've gone through the house, we checked the insulation, the attic vents, the basement everything. It sits on a flagstone foundation, it has wooden siding downstairs and the old asbestos siding upstairs. It's a smaller house.
My problem is in the spring, my house stays comfortable most of the day, but in the afternoon/ early evening it starts really getting warm in here. It will be between 70 - 75 outside and be 70 - 71 inside until about 5 or so when it starts heating up, and it just keeps getting warmer and warmer. I don't have any AC going, but some nights i have to turn it on because it gets so hot in here.
Last night it got up to about 75 outside during the day, but last night it was 55 outside at around 10, and it had climbed to 77 inside. At midnight it was 52 outside and 83 inside, it was too cold if I opened the windows, but as soon as I shut them it warmed right up again. I don't really know what to do, it's even worse upstairs, I don't have an AC unit for up there, it was over 88 up there last night. I'm at a loss as to why it gets so hot inside when it's getting chilly outside. In the summer it's not so bad, when it stays warm all day long, it still gets really warm upstairs then, but downstairs stays around 75 ish without the AC on.
In the winter my house is pretty good, I use less then half the heating oil my parents do, and their house is a little bigger then mine even, they live next door.
If anyone has any suggestions I'd love to hear them. The design of the house does not promote very good airflow at all though, the stairs run right through the middle of the house with just a small entrance-way at one end, so there is effectively 0 airflow from one half of the house to the other.


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## gregzoll

How well is the attic vented? Are the windows, doors & electrical outlets well sealed, to not allow air movement? How old are the windows & doors? How old is the hvac system. As for the attic, even if it is vented, it can still get up to 130 if there is no proper air movement.

We run our a/c down to 68 at night during cool but humid nights, otherwise it is at 70 during the Summer months from late June to Late august. If your a/c or fan is not running, air will get stale, and the house will feel warm. Especially if there is not enough air return back to the furnace. BTW, our house stays around the set temp of the thermostat all of the time. Right now it is 102 up in our attic, with a powered attic vent fan running. Without it, the attic would be at around 120-130 right now, and yes our house would feel warm, along with if I did not seal up around the windows, and put in good weatherstripping around the doors, and air seal outlets and receptacles.


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## furthermore

My windows are about 4 years old they were put in by the previous owner, when the house was "winterized" through some government program. I don't have central air, I have 1 wall unit AC downstairs. The Attic vents are good, no fan is up there but I store wood up there and it really doesn't get all that hot in there. I use my one upstairs room as my workshop and I go into the attic frequently to get more wood, or take a piece I don't need back up. While I don't have a temperature gauge up there, it's definitely better then my parents house.

My problem is only during the night though. All day long I can get away with just my ceiling fan in my living room. Then as soon as the sun starts setting the house heats up. I really don't understand it. My living room will be between 70 - 75 degrees F all day, then the sun goes down and the temperature shoots up. It's midnight here, 65 outside, and even with the windows open it was 88 degrees in here, 87 upstairs in my bedroom. At 4 pm today when it was 80 degrees outside and the sun was out it was only 75 in the same room with just a ceiling fan on at the lowest speed. I don't understand why the house heats up so much when the sun goes down.

That's really my only problem, it just gets very hot at night in here. It doesn't just feel hot, the thermostat shows the actual temperature rises at night. The temperatures I wrote previously are from the thermostat display, and my digital clock/weather station thing, not subjective temperatures. I guess when i think about it, it does it in winter too, just I never really complained about the house getting warmer on a cold winter night...lol. But if there is something I can do so I don't have to run the AC all night it'd be great.


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## HouseHelper

Are sure your heat is not running? Do you have any electric heat, either baseboard or ceiling/floor type that might be on?


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## Blondesense

We have a brick house (see avatar). Between the brick and the dark shingles it will absorb heat. Then like you, the temp often rises in the evening when you think things should be cooling off. Nice in the winter, not so nice in the summer. The original owner installed a full house attic fan. When we use it, it works well since we have an open floor plan, but we do run our A/C a lot.

Your fluctuations seem a bit extreme though.
Our heat uses propane, and even if the heat is not on, just the pilot will raise the temp in the house.

Trees can also help. You might also consider a lighter color shingle when it comes time.

Not an expert, but I would look into an attic fan of some sort.


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## user1007

I think an attic fan system would make a big difference for you. It will make things more comfortable for you and reduce the load on your AC unit. Part of what is happening has to do with basic laws of physics. During the day the temperature and weight/pressure of the air in the house are somewhat close to equal or that outside. Or outside is warmer and the air lighter. When evening settles in the colder and heavier air outside tries to sink and in essence forms sort of a barrier for the hotter air in the house trying to rise and escape. It gets trapped.

A thermostat control attic venting system (super important it have a shut off in case you ever had a fire) provides a forced air path for the hot air to exit.

Everybody thought my Northern California/Bay Area home had air conditioning but it never needed it since most evenings in the summer could be as much as 40 degrees cooler than daytime. Same thing happened as with your home though and as the temps fell outside the heat in the house built up. Insulation and good glass did its job but it was uncomfortable at night. I added a nice attic ventilation system and the problem went away instantly. 

Do make sure you line up a good HVAC person and roofer if need be to do the system for you. Last thing you want or need is a rooftop hack job. You want someone that can flash the units so they do not leak.


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## Okorsal

Don't listen to any of the comments above.. They simply don't have the experience. The reason why your house gets hot at night is because your house was built almost a century ago and it's all brick which means they never used insulation in between the walls. So during the day the sun heats up the bricks and at night it absorbs the radiant heat and brings it in the house. There is no simple way to fix this unless you tear down the plaster and install insulatation then re-plaster or drywall the walls in this case you might lose some square internal footage but that's the sacrifice your willing to take.. But it's not significant lossage of space. Good luck!


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## SeniorSitizen

During the evening hours open windows on the ground floor and if the upper level has double hung windows pull the top half down giving the warmer air an escape route. As the cool air enters the lower level the warm air will be expelled. For this to work the stair well must be open.


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## Yodaman

similar to what Sr said, but put a window fan in upstairs blowing out on the hottest end of the house. Open a window or two downstairs on the coolest side of the house. Darkening blinds on the hot side. No relief? Consider a Mini Split AC system


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## SeniorSitizen

Yodaman said:


> similar to what Sr said, but put a window fan in upstairs blowing out on the hottest end of the house. Open a window or two downstairs on the coolest side of the house. Darkening blinds on the hot side. No relief? Consider a Mini Split AC system


Rented an apartment in college years with a window fan. Forgot about that. Belt driven with 3 blades pitched so it would nearly suck your socks off. And those were TGODays.:laughing:


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## supers05

Okorsal said:


> Don't listen to any of the comments above.. They simply don't have the experience. The reason why your house gets hot at night is because your house was built almost a century ago and it's all brick which means they never used insulation in between the walls. So during the day the sun heats up the bricks and at night it absorbs the radiant heat and brings it in the house. There is no simple way to fix this unless you tear down the plaster and install insulatation then re-plaster or drywall the walls in this case you might lose some square internal footage but that's the sacrifice your willing to take.. But it's not significant lossage of space. Good luck!


My house is over 60 years old. Brick with Air gap and plaster walls. The Air gap is a form of insulation and does work. Just not as well as newer products. I have never seen this problem to this extreme. The "worse" is that my house will sit at the daily average temp all the time. Granted I live in a cooler climate but the OP does sound like an extreme example. I'm curious if there is any other source of heat in the house that's only on during the evening. (maybe lots of people?)


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## beenthere

Okorsal said:


> Don't listen to any of the comments above.. They simply don't have the experience. The reason why your house gets hot at night is because your house was built almost a century ago and it's all brick which means they never used insulation in between the walls. So during the day the sun heats up the bricks and at night it absorbs the radiant heat and brings it in the house. There is no simple way to fix this unless you tear down the plaster and install insulatation then re-plaster or drywall the walls in this case you might lose some square internal footage but that's the sacrifice your willing to take.. But it's not significant lossage of space. Good luck!



I wonder if he got it taken care of in the 3 years its been since he made this thread.


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## SeniorSitizen

But I'm sure glad it was rejuvenated so we don't forget there are those people that don't understand that insulation doesn't stop temperature transfer but only retards it.


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## beenthere

SeniorSitizen said:


> But I'm sure glad it was rejuvenated so we don't forget there are those people that don't understand that insulation doesn't stop temperature transfer but only retards it.


We should have an Insulation forum so people can find out. :laughing:


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## donaldlbjr

*house gets hot also in evening*

I am in a three year old house that is comfortable in the day with A/C on about 78 then when it cools off at night our house is still hot in fact it gets warmer at night then during the day. Our electric bill is double everybodies that lives within the community. Georgia power has been out numerous times and cannot explain it either. We have a spike in electric at about midnight to three of so when everybody is sleeping. Again no explanation. I believe all of this has something to do with the house heating up around midnight or so. During the day our attic is in the 130s and at night drops to around 90 or so. No fan but plenty of venting


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## NYSteelhorse

I feel the need to add that the explanations by #Okorsal and #Seniorsitizen are the explanations I've received also. I have a 100 year old 3½ story Brownstone in Brooklyn NY, that has a second brick building attached that architects say may be another 100 years older. All brick and plaster, the only insulation is in the roof. Windows are about 25yrs but get regular annual maintenance. I'm here for the same problem. Windows A/C's work overtime in the evenings. Comfortable days end up being unbearable nights and my wife complains she can't put on her makeup in the morning because she's sweating so much. It's heat soak and transfer making the house a large passive solar radiator. Great in winter if there's enough warming sun. But cold is absorbed and radiated as well. Not good. 

The best solutions I've found is retrofit insulation, good quality double pane windows, and mini splits for temp management. I can't insulate exteriors because of landmarks registry, so I'll lose interior space. The mini splits manage what's needed cheaply and my baseboard heat furnace isn't overtaxed during cold spells. ($1000/month winter gas heating bills are not unusual for me! Not ALL winter, but usually 1 or 2 months during.)


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