Hot answers tagged

60

Meet solar gain For the most vivid example of solar gain, sit in your car with everything off - A/C off, blower off, windows rolled up tight, doors shut tight. You can't. Your body will force you to open a door or something because it will become unbearably hot within minutes. If it were always night, or if your house were entirely in shade, this would ...


36

Because you have indoor heat sources There's a lot of reasons your house will get warmer than the outside temp, but this is the single largest one. The human body produces as much as 400 BTU (422 kJ) per hour at any given time, equivalent to 117 W. Your refrigerator can give off close to 500 BTUs (528 kJ) per hour (147 W). A TV can use about 20-30 watts, or ...


29

Since it's a "Heat in summer" problem, a traditional decorative and edible approach would be to train/trellis a plant or plants in front of the wall - grapes, vining tomatoes, espaliered fruit trees, perhaps even a fig depending on your climate - or purely decorative things like climbing roses, wisteria, or ivy - but ivy can be surprisingly aggressive, so ...


20

There are many options, but concrete is very dense and makes a great heatsink. You can try insulating and air-conditioning the inside, but this approach is costly, energy-intensive and overall wasteful. If you have room, I suggest planting a deciduous tree between the building and the path of the sun. During the warm season, the trees leaves will shade ...


14

The first thing you should do is insulate the roof. Even just gluing sheets of Celotex or your local equivalent will make a huge difference, though installing it in a proper ceiling would be better. This will reduce the solar gain from the roof. Depdning on the material, painting the roof white could also help quite a bit. The walls will also allow a fair ...


13

To be clear -- Concrete does not cause it to get warm. Concrete is a very good thermal buffer - it resists changes in temperature. This is a highly desirable trait in a passively heated and cooled home. Because if the home is cool, it will stay cool despite the sun. If the home is warm, it will stay warm despite the cold. Insulation on the outside of ...


13

Put a false wall in front of the existing outside wall and allow air to flow between the two. That will reduce the conducted heat into the room by a huge amount.


12

In addition to the other answers that address your question for the most part, there is one more possibility I can think of. It is possible that your AC is not only trying to get the inside temperature to the target,but also the humidity. Some high-end thermostats will have a humidistat built in, while it is a separate unit in other cases. Regardless, some ...


11

Keeping what is effectively a greenhouse cool in the summer is a heavy workload for any AC system. Your best bet is to prevent solar heat gain by blocking the light. Doing this with an opaque shade on the exterior will be the most effective option, though window tints or interior shades would also help. Of course anything that reduces heating in the summer ...


9

For the record, I tried it out myself. I installed the Cool-N-Save system on a 4-ton A/C unit that was scheduled to be replaced in three months. After that three month period in the middle of the summer, the positive effects of the system were negligible at best, and probably detrimental. There were no detectible savings in cooling costs nor increase in ...


9

If you open both the top and bottom about 3" the hot air goes out the top and cooler air comes in the bottom.


9

A dehumidifier is about the same as a window AC unit with both parts in the house, for most purposes. They draw just as much power as an A/C unit of similar size (or more if they happen to be old and inefficient.) Given that the required energy labeling on A/C units tends to promote a degree of of paying attention to that, and it's much less clear on ...


9

I think you're overestimating the energy benefits you can get from window films. Those are primarily indicated to reject ultraviolet radiation that can increase fading of indoor materials. You're also mistaken if you think that during the winter the heat gain from sunshine on poorly insulated windows can make up for the heat that is radiated back out of ...


7

You haven't mentioned what sort of fixture these bulbs are in, but this sounds like a classic case for compact fluorescent lights (CFL). Efficiency in light bulbs boils down to "for a given amount of power running through the bulb, how much is turned into light and how much is wasted as heat?" Fluorescent bulbs are much more efficient than incandescents; ...


7

There is an optional add-on part for HVAC systems called an economizer. An HVAC economizer is a dampered vent designed to save energy and give the cooling system a break. Sensors within the economizer compare the outdoor temperature and humidity with that inside the building. –Google When you call for cooling, the unit decides if it needs to run the AC ...


7

Because an Air Conditioner doesn't give any airflow between inside and outside. An AC is essentially a refrigerator. Inside is the conditioned space, and outside is the heat dump (i.e. the back of the fridge where it's hot) The heat is transferred from inside to outside via the liquid coolant - it evaporates inside, collecting heat due to the latent heat ...


6

What about an attic vent fan such as this one? It has a thermostatic control. Separate shutters are also available such as these. They open based on the air pressure generated by the fan. You would need to create "in" vents, preferably placed low on several walls to allow full air flow. These could be either fixed or shuttered, depending on whether you ...


6

I have been experimenting with using an old mosquito misting system to mist around one of my AC condensers. It does seem to make a small difference in energy consumption and reduce register temperature by around 1 degree. Not much but enough to help when the system is running constantly when we have parties at the house. The red circle on the attached ...


6

A 60-watt incandescent puts out about 800 lumens of light. A 100-watt incandescent puts out about 1600 lumens. Your 10 60 watters put out about 8000 lumens total. It'll only take 5 100-watt bulbs to equal that. 60 * 10 = 600 watts heat. 100 * 5 = 500 watts heat. So, if the sockets can handle it, your room will be a little cooler if you switch to using 5 ...


6

I would say a dehumidifier would not be a more efficient choice for summer comfort than turning down the thermostat on an A/C. Sure, the delta-T across exterior walls would drop, so somewhat less heat would seep in from outside, but as was already mentioned, the A/C then has to remove the dehumidifier's additional heat from the home (100% of the input power ...


6

I have about 50 55-gallon drums stacked in my basement, all filled with water. They are stacked one on top of the other (bottom row/top row) along our north basement wall. I have two in floor-mounted fans, one pushing, one pulling, mounted in the ground-floor joist cavity (from above they just look like floor mounted cold air returns). During the day, the ...


5

Rather than go full mobile-home park and start boarding (or foiling) up the windows, they do make window film specifically for this: Gila Heat Block Film (just one example) That film might be enough to fix the problem, and if you install it carefully, management will probably not care if you leave it in place when you move. If that alone doesn't block ...


5

There's nothing wrong with your thermal insulation design. Insulation is designed to isolate your inside temperature from the outside temperature. So your a.c. is set to 80°F (27°C), then at 3am the temp outside slowly drops to 76°F (24°C)... it will take hours for your inside temp to see the difference because you attic is still going to be hot. By the time ...


5

Trees ( maybe some other sorts of plants as well) near walls of buildings with sub surface basement, near terrasses, near concrete or plastered ways etc. can be a big problem in the long run, since the roots may destroy the sealing of a wall resulting in molded basements and health problems, and can lift and brake ways even made of concrete. The leaves or ...


5

TLDR: Not just no, but heck no. Throwing good money after very bad First, electricity costs: any dehumidifier old enough to use R-22 is also super inefficient as-built: The government's Energy Star program has really pushed/incentivized manufacturers to make appliances more efficient, and wow, have they ever done it! We constantly have people asking how ...


4

Solar curtains - beware I haven't seen any that look much better than aluminum foil.


4

To the extent that it matters at all (and it shouldn't, because there are fire-resistant walls between the garage and any living spaces), the extra load on the air conditioning is proportional to the temperature of the garage and nothing else. The heat flow from the garage into the house is proportional to the temperature difference between the two spaces, ...


4

You're looking for the V in HVAC (Ventilation). There are indeed systems that will pull in outdoor air, filter it, and supply it through the home. These systems would likely be in addition to any heating or cooling equipment, not as a part of them. To be specific, you're looking for a balanced ventilation system. Talk to your local HVAC company, they ...


4

The term you're looking for is "whole-house fan". It's a big fan that can blow outside air, inside. I have one in my house and they work very well for your use case. Be warned that whole-house fans are notoriously difficult to insulate and air-seal. When winter rolls around, the last thing you want is a huge hole in the side of your house through which ...


4

I think you'd end up running into a whole boat load of issues before you could even begin talking about efficiency. The first and most pressing being the rapid condensation that would occur within seconds of circulating the cold liquid (leaving you with a whole host of other DIY problems you'd need to work out). Which, I imagine would need to be somewhere ...


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