4 ms·

Last couple of summers we've had extended periods where my flat can reach a pretty uncomfortable temperature to work in. I do not want to install AC and have so

by smcl 5y ago

Last couple of summers we've had extended periods where my flat can reach a pretty uncomfortable temperature to work in. I do not want to install AC and have so far managed to counteract it by making sure my windows are open overnight to circulate cool air and by closing different curtains + blinds through the day (one half of my flat gets morning sun, the other half evening sun). This keeps the air in the flat comfortably below the outside temperature, but if I forget to do either of these steps the temperature can creep up a bit and it's not possible to cool it down until evening (and if it's super humid and hot it might not cool that much). I'm wondering if there's any low-energy or green solutions to this. I suspect I'm asking for something impossible or that the only way to improve this is to automate the blind opening/closing :-/

antupis 5y ago
https://www.ikea.com/us/en/cat/electric-blinds-44531/ https://www.ikea.com/us/en/cat/electric-blinds-44531/
- smcl 5y ago
  This looks good, as my blinds kinda suck too!
situationista 5y ago
There was an interesting article on heat pumps in the NY Times yesterday - they are similar to AC units but far more efficient, requiring far less electricity to run. Plus they work as heaters in the winter. I use heat pumps coupled to solar panels and draw very little power from the grid, if any. https://www.nytimes.com/2021/06/30/climate/heat-pumps-climate.amp.html https://www.nytimes.com/2021/06/30/climate/heat-pumps-climat...
- wffurr 5y ago
  Air conditioners are air source heat pumps.
  - amrcnimgrnt 5y ago
    Ya, Im very confused when people talk about heat pumps as separate from ACs. My new tenant got super excited when I used the word "heat pump" to refer to my AC.
  - g8oz 5y ago
    One way heat pumps
    - wffurr 5y ago
      Another term I've seen for "heat pump" is "reverse cycle air conditioner".
    - balfirevic 5y ago
      No, that implication is not universal in the term "air conditioner"
scrollaway 5y ago
> I'm wondering if there's any low-energy or green solutions to this. The answer is "it depends". How your flat is designed will have an impact on what you can do. But if you are able and willing to do some house work, there is a lot you can have control over. At the end of the day, it's all about how you can control humidity, the flow of hot and cold air and humidity. At your disposal, tools such as conductive materials, insulating materials, etc. Google "passive house" to see the concept and what these things use. With that said. Heat pumps are incredibly efficient, and replacing your heater with a reversible air conditioner which you can then run in both summer and winter will do far more for your overall energy efficiency than anything else you can do. Most of your energy consumption comes from winter-time heating. Start here for a good introduction to heat pumps and how they are so efficient: https://www.youtube.com/watch?v=7J52mDjZzto https://www.youtube.com/watch?v=7J52mDjZzto
pestatije 5y ago
Windows awnings: very good at keeping the sun out of a flat. You might have to ask your building manager for permission to install them though.
kwhitefoot 5y ago
Here in Norway awnings that extend automatically to shield the window from the sun are an off the shelf item, they also retract automatically if the wind gets too strong.
sharno 5y ago
Ceiling fan
clydethefrog 5y ago
Windows shutters. There's a reason all those Italian charming villages have them. http://www.shutterdesign.co.uk/blog/external-window-shutters-italians-love/ http://www.shutterdesign.co.uk/blog/external-window-shutters...
amrcnimgrnt 5y ago
If you live in a cold climate, buy a mini-split (a type of AC that also works in reverse). ACs are very efficient (more than 100%!). By using an AC to heat (a Delta(T) in my city of at least 30C) your home in the winter you more than offset the carbon to cool and dehumidify it a mere 5-10C (again, in my case). Heating a home in cold climates are far worse than cooling, but there's a puritan rejection of AC:. - The Delta(T) is larger to heat a home than to cool it. Delta(T) sets the heat loss through your walls. - There is an attitude that cooling is hedonistic, while heating is a necessity, but it's thermodynamically and metabolically far easier to heat than to cool. - Most heating is done with fossil fuel furnaces which are at best 90-95% efficient. A heat pump can be over 300% efficient [1] (i.e. it moves 3J of heat from the cold side to the hot side using only 1J). This is much better improvement in performance than an electrical car. Get an AC that can work in reverse, and if you want don't use it in the summer. EDIT (added following): [1] The metric here is coefficient of performance, COP = Thigh / (Thigh - Tlow). For 30C to 20C the theoretical maximum is 3 000%, or 30x [2] No, you can't break thermo laws with [1].
- smcl 5y ago
  Wow ok by an interesting coincidence I’m actually needing to upgrade my heating too (everyone moved off the building’s shared boiler, then voted to get rid of it at the one meeting I missed - hats off to them). Installing a new gas boiler and fitting it to the existing system means ripping up some of my (beautiful old and recently refurbished parquet) flooring so if this gives me a way to avoid that AND maybe cool the air relatively efficiently during the worst summer days I’ll definitely need to look into it!
  - amrcnimgrnt 5y ago
    Study it a bit while it's still warm and look up your local weather. [1] The COP gets worse as Delta(T) increases and heat pumps are nowhere near the theoretical best, so at a certain point it's better to use gas. But that's typically below 0F (-10C). I put in a four way Mitsubishi (2x as expensive but super silent) in my old home. Relatively happy with it, except I don't think the installers put enough coolant in it (it's best to instal a heat pump on a cool day). The air does gets a bit dry, so consider getting a heating humidifier for the night. Finally, if you can afford it and if you can install it, a heat-pump with buried coolant lines really multiplies the efficiency (since the ground is above freezing and acts as a heat store through the seasons) EDIT: [1] If you live near a large body of water, especially if it's salty, it's very unlikely your cold days are cold enough to be a problem for the AC. Unless you live in Thunder Bay. [2] AC is not a huge climate problem. Heating, cars, global supply chains, agriculture are bigger problems. AC just gets the attention because it's considered frivolous. A bigger problem is that modern homes are built with no consideration for cooling. My old house was 100 years old and naturally kept cool. My new house has at least 7 seven!!! skylights. It's impossible to cool. At least 5 of them face north :S

by smcl 5y ago

antupis 5y ago

https://www.ikea.com/us/en/cat/electric-blinds-44531/ https://www.ikea.com/us/en/cat/electric-blinds-44531/

smcl 5y ago
This looks good, as my blinds kinda suck too!

situationista 5y ago

There was an interesting article on heat pumps in the NY Times yesterday - they are similar to AC units but far more efficient, requiring far less electricity to run. Plus they work as heaters in the winter. I use heat pumps coupled to solar panels and draw very little power from the grid, if any. https://www.nytimes.com/2021/06/30/climate/heat-pumps-climate.amp.html https://www.nytimes.com/2021/06/30/climate/heat-pumps-climat...

wffurr 5y ago
Air conditioners are air source heat pumps.
- amrcnimgrnt 5y ago
  Ya, Im very confused when people talk about heat pumps as separate from ACs. My new tenant got super excited when I used the word "heat pump" to refer to my AC.
- g8oz 5y ago
  One way heat pumps
  - wffurr 5y ago
    Another term I've seen for "heat pump" is "reverse cycle air conditioner".
  - balfirevic 5y ago
    No, that implication is not universal in the term "air conditioner"

scrollaway 5y ago

> I'm wondering if there's any low-energy or green solutions to this. The answer is "it depends". How your flat is designed will have an impact on what you can do. But if you are able and willing to do some house work, there is a lot you can have control over. At the end of the day, it's all about how you can control humidity, the flow of hot and cold air and humidity. At your disposal, tools such as conductive materials, insulating materials, etc. Google "passive house" to see the concept and what these things use. With that said. Heat pumps are incredibly efficient, and replacing your heater with a reversible air conditioner which you can then run in both summer and winter will do far more for your overall energy efficiency than anything else you can do. Most of your energy consumption comes from winter-time heating. Start here for a good introduction to heat pumps and how they are so efficient: https://www.youtube.com/watch?v=7J52mDjZzto https://www.youtube.com/watch?v=7J52mDjZzto

pestatije 5y ago

Windows awnings: very good at keeping the sun out of a flat. You might have to ask your building manager for permission to install them though.

kwhitefoot 5y ago

Here in Norway awnings that extend automatically to shield the window from the sun are an off the shelf item, they also retract automatically if the wind gets too strong.

sharno 5y ago

Ceiling fan

clydethefrog 5y ago

Windows shutters. There's a reason all those Italian charming villages have them. http://www.shutterdesign.co.uk/blog/external-window-shutters-italians-love/ http://www.shutterdesign.co.uk/blog/external-window-shutters...

amrcnimgrnt 5y ago

If you live in a cold climate, buy a mini-split (a type of AC that also works in reverse). ACs are very efficient (more than 100%!). By using an AC to heat (a Delta(T) in my city of at least 30C) your home in the winter you more than offset the carbon to cool and dehumidify it a mere 5-10C (again, in my case). Heating a home in cold climates are far worse than cooling, but there's a puritan rejection of AC:. - The Delta(T) is larger to heat a home than to cool it. Delta(T) sets the heat loss through your walls. - There is an attitude that cooling is hedonistic, while heating is a necessity, but it's thermodynamically and metabolically far easier to heat than to cool. - Most heating is done with fossil fuel furnaces which are at best 90-95% efficient. A heat pump can be over 300% efficient [1] (i.e. it moves 3J of heat from the cold side to the hot side using only 1J). This is much better improvement in performance than an electrical car. Get an AC that can work in reverse, and if you want don't use it in the summer. EDIT (added following): [1] The metric here is coefficient of performance, COP = Thigh / (Thigh - Tlow). For 30C to 20C the theoretical maximum is 3 000%, or 30x [2] No, you can't break thermo laws with [1].

smcl 5y ago
Wow ok by an interesting coincidence I’m actually needing to upgrade my heating too (everyone moved off the building’s shared boiler, then voted to get rid of it at the one meeting I missed - hats off to them). Installing a new gas boiler and fitting it to the existing system means ripping up some of my (beautiful old and recently refurbished parquet) flooring so if this gives me a way to avoid that AND maybe cool the air relatively efficiently during the worst summer days I’ll definitely need to look into it!
- amrcnimgrnt 5y ago
  Study it a bit while it's still warm and look up your local weather. [1] The COP gets worse as Delta(T) increases and heat pumps are nowhere near the theoretical best, so at a certain point it's better to use gas. But that's typically below 0F (-10C). I put in a four way Mitsubishi (2x as expensive but super silent) in my old home. Relatively happy with it, except I don't think the installers put enough coolant in it (it's best to instal a heat pump on a cool day). The air does gets a bit dry, so consider getting a heating humidifier for the night. Finally, if you can afford it and if you can install it, a heat-pump with buried coolant lines really multiplies the efficiency (since the ground is above freezing and acts as a heat store through the seasons) EDIT: [1] If you live near a large body of water, especially if it's salty, it's very unlikely your cold days are cold enough to be a problem for the AC. Unless you live in Thunder Bay. [2] AC is not a huge climate problem. Heating, cars, global supply chains, agriculture are bigger problems. AC just gets the attention because it's considered frivolous. A bigger problem is that modern homes are built with no consideration for cooling. My old house was 100 years old and naturally kept cool. My new house has at least 7 seven!!! skylights. It's impossible to cool. At least 5 of them face north :S