Decades ago, people predicted that we'd live underground by now because global warming would make the surface unlivable.

They didn't count on us being such assholes that we'd burn more fossil fuels to run AC year-round, fighting global warming with more global warming.

@stavros I'm getting a bunch of ACs installed right now as we speak. But does it help when I mention I already got solar panels installed on my roof?

@trinsec @stavros About the solar panels - if you you are using any form of grid-tied solar panel installation - you are adding additional strain on the electricity grid for balancing (additional power plants that have to be kept just in case and the additional effort for managing the grid, plus grid hardware upgrades). See this report in the section "Whole system costs" (near the end):
See how the blue diamonds on the graphic are above the price for Solar and Wind power plants. The bars represent the price to produce. The diamonds represent the price to produce plus the costs for balancing.

About the AC installation - it's a lot better to invest in highly upgraded building thermal insulation and high quality windows. So in the summer will be a lot cheaper to keep it cool and in winter - to warm the space. Here is a good video introducing the concept of a "passive house". There are other interesting moments: With good insulation and air-tightness you need ventilation system to supply fresh air to the space. It's a air filter, big fan, heat exchanger, piping and ducts. Heat exchanger helps to not throw away outsid warm air and in the winter/cold air in the summer. The fan requires very little power (50-60 Watts). So with this system you get fresh clean air and get free clothing dryer. And the power consumption is a lot less - the electric dryer eats a lot of energy - 2-3 kiloWatts (2000-3000 Watts per cycle). So we can run the fan of the HRV for 40 hours with 2000 Watts.

Here are all of the requirements one building to be considered "passive house":
Note how simple they are: heating/cooling energy demands per square meter, airtightness and thermal comfort (not allowing overheating)

@_1751015 @stavros Eh, you call it simple, but this will be more expensive than installing the ACs. This is an old badly isolated 60s rowhouse with not much space to do stuff in. That passive house looks massive compared to my place. I do have plans to replace the south-facing windows for better insulating ones, to get awnings, and to look into better insulation in general. But it is all $$$. I can only do one upgrade every 2 years. A fact is that we face more and longer heatwaves, ACs is a direct solution at least. And especially when there are more and more solar panels in my neighbourhood and my panels can't deliver much power back anymore on the most sunny days like they did last year because of too much power in the grid, at least they'll be able to be used to their full potential when I have the AC on and running. Otherwise it is wasted power. Though I've understood that our powergrid is going to face some changes to be able to handle all this eventually. (Solar panels are heavily subsidized here). In general I'm already trying to take steps in saving energy, but there are limits.

@trinsec @stavros IMO there are some points that should be mentioned. They bring important details about the topics.
1) About "installing the AC units": you are forgetting the running costs. With insulation and/or windows upgrades you don't have the big running costs of an AC unit. Also we need to take into account the depreciation: one window will work for around 30 years with very little maintenance. Air conditioner unit will work around 10 to 15 years. Of course, if you are paying a rent this calculation doesn't matter. Or if your planning horizon is short (1-3 years).

There is an interesting Commissioned study about the :

They mention the following (- Section 2.6.3):
"Most consumers base their choice of equipment rather on purchase price and other factors like availability, service and 'trusted' brand names than energy cost. Few people realise
>>that energy cost can be up to 70%-90% of total life cycle cost <<
(which includes purchase, installation and maintenance)."

2) About the "more available solar panels": electricity grid with given amount of renewable energy sources requires additional power plants with the same power to provide power reserve (in particular a "hot reserve"), regulate the network phase and frequency. Wind and solar can't provide these functions, only hydropower can (from the renewable energy sources). But it comes with some serious restrictions - there are very few suitable places where hydropower plants can be build. There are other serious matters around them. Currently most countries are "solving" this challenge by building power plants that burns natural gas and uses gas-turbines. The other frequently used "backup" power source are the nuclear power plants.


@trinsec @stavros

The energy consumption of ACs is very high. The smaller units are consuming around 1600-2000 Watts at max power. For one hour of operation this is 1,6 to 2KWh. You need about 6-7 very efficient (300 and more Wp) solar panes (dimensions of 1,65 meters by 1 m) to produce this amount of energy for 1 hour. That's a lot of panels and a lot of required space for installation.

3) About the heatwaves and the solution:
I don't know in what country/climate you are living. I'll give you detailed data for where I'm living.
The first attachment gives the temperatures in C of the UPS in my place. Subtract around 5C degrees to get the indoor temperature. The place is a flat in big building, surrounded by other flats - very small area of the walls are external. They face North and South. The UPS is situated in a corridor around the geometric centre of the floor plan. It is almost equally far from the south and north external walls.
The second image is the outdoor temperature in Sofia, Bulgaria. For example let's see the peak in May, 2020. Outdoors is 34C max, UPS is 31C - so indoors is 31-5=26C.

Quite comfortable indoor temperature and it's holding there without AC. However these kind of temperatures require the usage of curtains - we use a tick curtains of 60% cotton and 40% linen and they cover the almost the entire height of the southern walls.


@trinsec @stavros
3/2 (I've underestimated the amount of text)

The renovation was around 10 years ago - external insulation for the walls, new double glazed windows with aluminium frames, new entry door with good sealing at the edges.
My rough calculations give U-values around 0,3-0,35 W/m2K (Watt per square meter per 1 Kelvin temperature difference)(the North-facing walls have some internal insulation also), the windows are around 2,0-2,7 W/m2K (one has the additional energy coating). These values roughly translate to the German standard ENEV 2002 (the third image, taken from, page 13 of the PDF).
The easy upgrade path for this place is to replace the double-glazed glass with triple-pane glazing. Utilizing E-coatings and wide glass spacing (around 40mm total depth of the glass package) we could go at around 0,9-1,0 W/m2K. This upgrade should cut around 50% of the total heat losses (or gains in the summer) because the window area is almost 50% from the total outdoor-facing surfaces and because the losses are currently significantly bigger there.

We have 10 C or Kelvin temperature difference(25 indoor, 35 outdoor) and 10 sq.m of glazing.
in the case of U-value of 2,7 this gives us:
10 (temp diff)*10 (area of the glazing) * 2,7 = 270 W are flowing through the window into the room at the given temperature difference (10 degrees C).
With U-value of 1,0 we get:
10 (temperature diff) * 10 (sq. meters of glazing) * 1,0 = 100 Watts of power heating the same room.

Let's compare them: with the better windows the room will get the same amount of energy about 3 times longer - 3 hours for the better windows vs 1 hour for the base scenario. 300 Wh of energy (300 watts of power for 1 hour) is not insignificant amount.

@trinsec @stavros
I've forgot about the expenses and costs back then:
because there is relatively small area facing outdoors the costs are not very high. The AC unit power for the area when not insulated would be one 9000 BTU and one 18000 BTU units:
1) the windows (around 13 sq.m) - the price of 2 cheap or 1,4 high-quality AC units with inverter;
2) the external thermal insulation (around 35 sq.m) - around 10% more than the windows.

So far (10 years) I had to replace 2 (two) handles and two separate details of a scissors/tilt mechanism.

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