Experimenting with Air Conditioning

Reading Time: 3 minutesI live in a Minergie, which, in theory, means that I never need to worry about climatisation because the building keeps itself warm in winter and cold in summer. In practice the features that make a flat fantastic winter make it awful in summer.

## Good in Winter

Large windows, in winter allow heat radiation in, so you use the sun to heat your apartment. From Spring until Autumn it has the opposite feature. It turns a room into a sauna, rather than giving an enjoyable temperature.

The cheapest solution is to close the windows and shutters on the hot side, and keep the cool air in. Once 1300 has come and gone you switch to opening windows on the opposite side, and open windows on the shady side, now that it’s shady.

## Solar Accumulators

The issue comes when the veluxes on the sunny side become solar accumulators. The velux for the stairs, and bathroom have no cover, so when it’s hot they let the heat radiation in, and when you’re on the top floor the rooms heat to 32°c or more.

That isn’t the real issue. The real issue is that the specific heat capacity of the Minergie building is huge. This means that once the core of the building heats up you can open windows but unless they’re wide open the heat inertia from the building will heat that room within minutes of windows being closed. That is the case even when it’s 15°c outside.

## Inadequate Venting

In a well designed minergie building you would take the cool outdoor air and blast the hot rooms in the building to control how hot they get in summer.

For years I refused to play with air conditioning because although one side is nice and cool, the other side of the air conditioned air is hot and muggy.

Last night I played with air conditioning and I was struck by two things. The first is that although the exhaust from the AC unit was warm, it dissipated quite fast. I was using the AC to cool one room, and open windows to vent the hot air with a fan to speed up the process. Ideally I would cool the structure as well as the slab of glass from the Velux. It stores a lot of energy via the afternoon sun.

My goal when playing/experimenting with air conditioning is not to get the apartment to be at 21°c or 23°c. My aim is just to get it to 27°c from 32°c or more. My aim is to cool the walls and the structure enough so that when I want to sleep I do not “glow” to use the female term, or sweat to use the male term, when just sitting or lying down.

The temperature is meant to peak at 30-33°c over the next few days, hence the reason for my playing with air conditioning. When I came back from several days of not opening windows I found that my apartment heated up, without air being circulated. My aim, over the next four nights is to cool the apartment enough to be at 27°c or lower, and comfortable. 30°c is my new maximum.

In an ideal situation minergie would be setup so that when it detects that a room is above 27°c it starts to cool things down automatically. Opening windows works, but in a minergie building you would expect it to cool automatically.

## And Finally

Living on the top floor of all buildings will be hot. The bad habits of those in the flats below and next door, during a heatwave, will spread upwards to make the top floor very warm. The simplest solution is to open the veluxes and leave them open for several months in a row. I don’t want to do that because of mosquitos, rain, and spiders. I have already seen three large, hairy spiders so I’d rather not see a fourth.

I am using air conditioning over the next four nights, because of the heat wave and then I will revert to opening the velux at dawn, and dusk to vent the hot air, and invite in cooler air. After five or more years of heat I am used to it.