Living with a single hose portable air conditioner

Today I'm not feeling well, so I decided to write a post. Warning, this is more some rambling to get my head cleared and maybe feel a little better.

Outside the heat is scorching. I've been adapting my mobile air conditioner unit to hopefully optimize its efficiency. You may ask why I don't have a regular air conditioner. You see, I'm living in a first world country where people are not allowed to have air conditioners without a permit. And getting a permit is strict. If you have ever been to Asia, you may have seen big multi apartement buildings with lots of AC's outside of their windows. That's not possible here in Vienna, Austria. The official ministry for building permits in Vienna has the following rule:

Die Montage von Split-Klimageräten ist zulässig, wenn sie nicht aus dem öffentlichen Raum (z. B. hinter einer Balkonbrüstung) eingesehen werden können. Ebenso müssen Klimageräte auf Dächern hinter einem Sichtschutz errichtet werden. Der Sichtschutz muss entweder an die Dachdeckung oder eventuell an die dahinterliegende Kaminaufmauerung angepasst werden.

Freely translated from German: The installation of air conditioners with a split system is only allowed if you can't see it from public space (permited behind visual covers like on balconies). Air conditioners on roofs also have to abide by this rule.

Building with air conditioners

Like many people in Vienna, I don't have a balcony to hide an air conditioner. Installing the air conditioner on the roof of a multi apartment building is probably way more expensive and requires a lot more bureaucratic effort to get a permit from all parties involved.

What people use here in Vienna are these energy inefficient monoblock air conditioners with a single hose. But, I think they are not very green as Germany, one of the biggest countries in Europe, gets lots of its energy from Coal-fired power stations. With the free trade of electicity within Europe, you can't really say that your air conditioner is powered by green energy. Why? Let's say you turn it on during the night. There would be no sun and during the night the wind usually subsides. So you can be sure that your green energy isn't really "green".

Source: EIA

These air conditioners can waste up to 1500W/h. Because they are so inefficient, they basically run all day. The only advantage that they provide is to keep the heat from rising too high and removing the moisture from the air which makes staying in a 25C/77F warm room with 52% relative humidity much more pleasant than a non air conditioned room with 65-70% relative humidity and 29C/84F because you want to keep the hot air outside by keeping the windows closed.

Energy consumption of my single hose air conditioner at full speed

My portable air conditioner uses about 1200W/h according to my 10€ energy consumption meter.

My optimized single hose air conditioner

Optimized single hose air conditioner

First we have to understand how these single hose air conditioners work. Basically they have a little compressor inside to transfer heat from a source location to a destination location. For the single hose portable air conditioner without any modifications this would be taking the heat from the inside air and transfering it to the inside air. This heated up inside air is then expelled by the single hose. But by expelling the air, you basically create a vacuum. Now there are 2 possibilities. You are either living next to a little ice cave that is directly connected to your house so that the expelled air is replaced by fresh cool air from the cave. The second option is that you live in a multi apartment building with a stair case enclosed with glass, raising the air temperature like a greenhouse. This air is then sucked into your room.

The other day I modified my air conditioner to channel the hot outside heat right back at the compressor to heat up the outside air instead of the cooler inside heat. Compared to last year, I don't really see a difference. Last year I didn't have this system and couldn't get below 22C/72F either. So I probably wasted my time optimizing my air conditioner.

My thermometers shows me that air with 32C/90F is being sucked in. The air being expelled is about 46C/115F. Inside I have about 24C/75F and the air conditioner produces 7C/45F cold air right at the exhaust.

But honestly, look at this "abomination" that is allowed here in Vienna. The city started a new initiative to cool buildings with "Fernkälte" (district cooling) but its primary target audience are new office buildings or government buildings. They use the garbage burning facilities to produce the cold water, but honestly I don't know if such a central system is so much more cost efficient. Would it be better to rely on existing electricity infrastructure and to allow every person use their own air conditioner? In software development it's comparable to leveraging a monolith to run the whole system, but monoliths are somewhat outdated today. By the way, I started to write a little bit about PHP on, if you are into that. Well, anyhow, let's just hope this summer is over sooner than later. I'm already feeling a lot better :-)

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