Green Building Forum - Air Con Mon, 05 Oct 2026 23:27:27 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Air Con https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310901#Comment_310901 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310901#Comment_310901 Sun, 28 Jun 2026 13:44:21 +0100 Rex
There was a recent article in the newspaper regarding the a/c numbers in different countries. Japan (my wife is Japanese) has around 91% domestic a/c installations, the UK, less than 5%.

My wife is really, really keen to get an a/c in our house. 3g, 180mm of Warmcel insulation; I don't think it is going to happen as I'm not drilling large holes through the glazing or walls. She even thanks we could replace one of the 'smaller' glazing panels to accommodate the a/c pipe. No way Jose!!!

Her further research finds this kind of unit: https://nessally.co.uk/ Apparently, according to her, they are very popular and very good. My feeling is, it is all marking hype and a money making scam.

Is there any 'new' technology that makes these portable a/c units as good as the blurb suggests? Are they generally any good or essentially, just an expensive fan that will be in the skip in a few years time?

Grateful for your thoughts and opinions.]]> Air Con https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310903#Comment_310903 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310903#Comment_310903 Sun, 28 Jun 2026 15:45:03 +0100 djh Posted By: RexMy wife is really, really keen to get an a/c in our house. 3g, 180mm of Warmcel insulation; I don't think it is going to happen as I'm not drilling large holes through the glazing or walls. She even thanks we could replace one of the 'smaller' glazing panels to accommodate the a/c pipe. No way Jose!!!
Air con units generally don't need "big" holes. They are usually split units connected by refrigerant and condensate pipes, which are narrow diameter. The exceptions are portable air-cons, which have large diameter air hoses, and monobloc units, which sit on a wall inside the house and have two large diameter air holes through the wall to the outside.

Portable air-cons require passing the hoses through an open window, and they generally provide a sealing kit to fill the rest of the gap. Whether that works well depends on what type of opening windows you have.

Her further research finds this kind of unit: https://nessally.co.uk/ Apparently, according to her, they are very popular and very good. My feeling is, it is all marking hype and a money making scam.
It's certainly a money-making product. AFAICT, it's a fan in a container with a wet rag. Avoid!]]> Air Con https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310904#Comment_310904 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310904#Comment_310904 Sun, 28 Jun 2026 16:25:04 +0100 philedge Posted By: Rex Japan (my wife is Japanese) has around 91% domestic a/c installations, the UK, less than 5%.

Do you know if the Japanese AC units are commonly used for heating aswell as cooling. If they are used for heating that may account for the high percentage of installs??]]> Air Con https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310905#Comment_310905 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310905#Comment_310905 Sun, 28 Jun 2026 20:11:42 +0100 revor blockquote>Posted By: djhPortable air-cons require passing the hoses through an open window, and they generally provide a sealing kit to fill the rest of the gap. Whether that works well depends on what type of opening windows you have.

This popped up on my PC yeterday. Great I thought just what I need was the conclusion in the 1st few minutes but not much good if I need to leave the house. Initially thought could run it off the solar PV during the day and in winter use to heat the conservatory using solar battery charged overnight. Don't fancy leaving windows or doors unsecured.

https://www.youtube.com/watch?v=D5ApvRis9X8]]> Air Con https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310906#Comment_310906 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310906#Comment_310906 Sun, 28 Jun 2026 20:34:57 +0100 djh Posted By: philedgeDo you know if the Japanese AC units are commonly used for heating aswell as cooling. If they are used for heating that may account for the high percentage of installs??I think the high humidity is likely to be a more important factor, along with the generally higher summer temperatures.]]> Air Con https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310911#Comment_310911 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310911#Comment_310911 Tue, 30 Jun 2026 08:11:07 +0100 Rex
But of course, most Japanese houses are virtually all timber and do not have a lot of insulation. But Japan does have a lot of high mountainous area and the northern islands are essentially, cold. so I assume that insulation is considerably greater.

Where I lived, virtually all properties had 'bolt on' a/c and heating was portable gas fired units. Interestingly, all gas units (heating, bath heating and cooking) have some kind of built-in accelerometer valve, which in the event of an earthquake, closes the valve. In an earthquake, fire is a major consideration, particularly when the majority of homes are timber.]]> Air Con https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310912#Comment_310912 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310912#Comment_310912 Tue, 30 Jun 2026 08:48:45 +0100 fostertom Air Con https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310913#Comment_310913 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310913#Comment_310913 Tue, 30 Jun 2026 09:17:21 +0100 Rex
Traditional Japanese houses did not heat the entire house; instead, they relied on zonal heating, warming only the specific room or area where people were located. This was achieved using centralized hearths, portable charcoal burners, heavy quilts, and specific architectural designs to trap warmth.

My wife is still banging on about getting some kind of cooling or a/c. We do have a MVHR fitted; personally, I have yet to believe that when running in the winter, it is really providing much warmed air, but I guess the temp is raised a little.

Would there be a way to use the ducting to pump chilled air through the house. I guess that would mean disconnecting the MVHR unit for the summer but it would all be in the loft and out of sight.

The other think I dislike about a/c is that all the windows have to be closed, all the time. I do prefer fresh air, even if it is warm air.]]> Air Con https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310914#Comment_310914 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310914#Comment_310914 Tue, 30 Jun 2026 09:39:56 +0100 fostertom Posted By: RexThis was achieved using centralized hearths, portable charcoal burnersOK - like anywhere - but in all-timber/paper houses, I'da thought fire risk would preclude ...]]> Air Con https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310915#Comment_310915 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310915#Comment_310915 Tue, 30 Jun 2026 09:42:15 +0100 fostertom Posted By: RexWe do have a MVHR fitted; personally, I have yet to believe that when running in the winter, it is really providing much warmed air, but I guess the temp is raised a littleI think not - the input air, though warmed, is by definition at (slightly but noticeably) lower temp that the general house aka outgoing air. Unless you put an inline elect heater into the duct, which is a common way to provide that 'extreme few days' backup that's part of PH.]]> Air Con https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310917#Comment_310917 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310917#Comment_310917 Tue, 30 Jun 2026 11:20:58 +0100 djh Posted By: RexWe do have a MVHR fitted; personally, I have yet to believe that when running in the winter, it is really providing much warmed air, but I guess the temp is raised a little.

Would there be a way to use the ducting to pump chilled air through the house. I guess that would mean disconnecting the MVHR unit for the summer but it would all be in the loft and out of sight.

The other think I dislike about a/c is that all the windows have to be closed, all the time. I do prefer fresh air, even if it is warm air.As Tom has said, MVHR does not warm the house. it just cools it more slowly than 'natural' ventilation (in winter) (and vice versa in summer). MVHR provides air for ventilation, so you breathe fresher air than in most houses.

Air is very poor as a heat transfer medium, so you can't use ventilation air to heat or cool your house, unless it is a passivhaus that is specifically designed to permit that. Forced air heating (and cooling) systems use much greater air flow rates than MVHR systems, with larger ducts operated faster and more noisily.

Preferring to have windows open for 'fresh air' rather than trusting your MVHR system to provide fresh air is not logical but totally understandable. You just have to consciously tell yourself that you trust the physics.]]> Air Con https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310918#Comment_310918 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18449&Focus=310918#Comment_310918 Tue, 30 Jun 2026 12:34:34 +0100 marktime