Aircon verses Underfloor cooling

[William C F Pierce]

As running Aircons is expensive. Has anyone thought of of converting an underfloor heating system to underfloor cooling, without the heating, but utilising the pumping system with "glycol" and a chiller. The way this would ideally be installed, is fitting it to the upstairs floor of a house. Based on the principle that hot air rises and cool air falls. As underfloor heating is cheaper to run than other heat systems. Theoretically cooling would be cheaper to run than an Aircon. The system would be effective on both upper and lower floors. I have approached a rep of one of these companies in the UK and he thought the adaptation was feasable. The basic cost of a heating floor overlay system is about £800 to £1500 for an average house, excluding labour costs, as it is easy to do it DIY. I have  previously done my own heating in the UK. Does anyone foresee any problems with this?

 

[Strange]

So basically you would be cooling the floor itself similar to floor heating? Like the floor and your feet would be cold/hot but its not actually 'heating/cooling' the house? 

 

I might be missing what you are after but if what I said above is true it won't be actually cooling the room IE pulling warm air from the top, across the evaporator and removing humidity and heat in an actual cooling cycle. 

[Karlo]

Just did a Google search and found this site dedicated to underfloor cooling..

http://www.thermo-floor.co.uk/underfloor-cooling.html

they state... 

It Is More Cost Effective

Thermo-Floor underfloor cooling systems are more cost effective and energy efficient than air conditioning as the outside of the building accumulates less heat therefore reduces heat build up and consequently reduces energy consumption.

[Crossy]

I would be worried about condensation, all that water that comes out of your A/C drain will now be condensing on your cold floor (or not condensing at all and leaving the air wet and clammy).

 

Thanks for the link Karlo, that site is interesting in what it doesn't say, there is absolutely no quantitative data comparing conventional with underfloor heating / cooling.

 

Quote

It Is More Cost Effective

Thermo-Floor underfloor cooling systems are more cost effective and energy efficient than air conditioning as the outside of the building accumulates less heat therefore reduces heat build up and consequently reduces energy consumption.

 

What does the above actually mean? I know what it says, but how does the outside of the building accumulate less heat, we're not controlling the sunshine?

 

Underfloor heat works so well because the warm floor heats the air above it causing it to rise and force the cooler air to fall and get heated, natural circulation. Cool air near the floor isn't going anywhere without some sort of stirring mechanism (possible just people moving around) so I see potential issues with stratification, nice and cool on your legs, blistering hot on your head.

 

 

[ClutchClark]

4 minutes ago, Crossy said:

I would be worried about condensation, all that water that comes out of your A/C drain will now be condensing on your cold floor (or not condensing at all and leaving the air wet and clammy).

 

Thanks for the link Karlo, that site is interesting in what it doesn't say, there is absolutely no quantitative data comparing conventional with underfloor heating / cooling.

 

 

What does the above actually mean? I know what it says, but how does the outside of the building accumulate less heat, we're not controlling the sunshine?

 

Underfloor heat works so well because the warm floor heats the air above it causing it to rise and force the cooler air to fall and get heated, natural circulation. Cool air near the floor isn't going anywhere without some sort of stirring mechanism (possible just people moving around) so I see potential issues with stratification, nice and cool on your legs, blistering hot on your head.

 

 

 

Excellent post. 

Thorough understanding of the principles at play.

[juehoe]

Radiant cooling is very interesting and I also looked at it.

As other mentioned, you should use cooled ceilings and not floors for best effect.

We have a temple with big concrete water tanks under the floor. This has a remarkable cooling effect - when you sit on the floor...

The main problem is indeed humidity. Radiant cooling don't dry the air as air conditioning systems do. The temperature of the cooling surface has to be about 4 degrees Celsius about the dew point. Otherwise you get water condensed, means wet surfaces which has to be avoided in any case.

Unfortunately the dew point is well above 20 degrees Celsius in Thailand.

The other problem is to find somebody in Thailand who can layout and build such a system.

I would recommend to build a well insulate house (walls, ceilings, windows) and use modern inverter air conditioning systems. Some of them allow to direct the cool air towards the ceiling which creates a radiant cooling effect - after the air is dried.

[Crossy]

Yeah, juehoe a different method of heat transfer to underfloor heating (which is mostly convection driven) https://en.wikipedia.org/wiki/Radiative_cooling

 

I saw that the website states radiative cooling (as opposed to convection) but none of the black-body radiation charts get anywhere near the temperature differentials we are looking at as they're more aimed at hot bodies. I guesstimate that one could achieve about 100W/m² of chilling. Enough? Possibly.

 

Thing is, radiative cooling cools a body (you) rather than the air the body is surrounded by which cools by convection.

 

I'd like to see more science before committing to a system which may or may not be adequate here.

 

[tutsiwarrior]

3 hours ago, Crossy said:

 

I'd like to see more science before committing to a system which may or may not be adequate here.

 

 

 

yeah...me too...all the AC processes that I know of use a convective air cooling mechanism...

 

domestic heat loads on the other hand are attributable mostly to radiation from the sun, conduction thru building materials and then the interior surfaces heating the air by natural convection...

 

 

Edited November 24, 2016 by tutsiwarrior

[CGW]

One factor worth considering is that cold floors are not "comfortable"! our granite floors in Isaan during the winter months get quite cool and are not comfortable unless you are wearing socks/shoes!

[Crossy]

8 minutes ago, CGW said:

One factor worth considering is that cold floors are not "comfortable"! our granite floors in Isaan during the winter months get quite cool and are not comfortable unless you are wearing socks/shoes!

 

If you are using the suggested ground-source heat pump you can flip the switch and have toasty warm floors instead :)

 

[Naam]

9 hours ago, Crossy said:

I would be worried about condensation, all that water that comes out of your A/C drain will now be condensing on your cold floor (or not condensing at all and leaving the air wet and clammy).

bingo! but might work in Riyadh, Baghdad, Tehran and Phoenix, Arizona.

 

[William C F Pierce]

Thanks for the many interesting replies. I did mention it should be on an upper floor.  This would allow cold air to fall from the ceiling to create the circulation on the lower floor. Like Aircon you can vary the temperature to suit your own comfort zone. The system can be imported and done DIY. Any concerns as to the bedrooms being to cold on the floor at night. Carpeting is an option. The link provided provided give a good indication as to it being more cost effective. It is also possible to have a non-electric dehumidifier if the dew point is of a concern.

On 23/11/2016 at 3:26 PM, Karlo said:

Just did a Google search and found this site dedicated to underfloor cooling..

http://www.thermo-floor.co.uk/underfloor-cooling.html

they state... 

It Is More Cost Effective

Thermo-Floor underfloor cooling systems are more cost effective and energy efficient than air conditioning as the outside of the building accumulates less heat therefore reduces heat build up and consequently reduces energy consumption.

 

[Carib]

Walk on a cold floor for a day when it is really "cold" in the wet season, I cannot do it, my feet start to hurt and I have to wear flip flops indoors. A cold floor is not nice at all IMHO, condensation has already been mentioned too.

[Crossy]

3 hours ago, William C F Pierce said:

Thanks for the many interesting replies. I did mention it should be on an upper floor.  This would allow cold air to fall from the ceiling to create the circulation on the lower floor. Like Aircon you can vary the temperature to suit your own comfort zone. The system can be imported and done DIY. Any concerns as to the bedrooms being to cold on the floor at night. Carpeting is an option. The link provided provided give a good indication as to it being more cost effective. It is also possible to have a non-electric dehumidifier if the dew point is of a concern.

 

Wouldn't putting carpet down sort of negate the radiation effect?

 

And I still don''t understand this statement from the website:-

"Thermo-Floor underfloor cooling systems are more cost effective and energy efficient than air conditioning as the outside of the building accumulates less heat therefore reduces heat build up and consequently reduces energy consumption."

It states that it's more energy efficient, but doesn't give a remotely scientific reason why.

 

If you decide to give it a go, do let us know the costs, maybe we are all wrong.

 

EDIT Black-body radiant heaters do work very well to make you feel warm without significantly heating up the space they're in, but they operate with temperature differentials significantly greater than one would tolerate in a cooled floor (think severe frostbite).

 

[Estrada]

I thought seriously about under-floor cooling systems, but then I got cold feet.

 

Hot air rises, cold air falls, so cooling must be at the top

 

This is also why heating systems may be positioned under-floor (hot air rises). It is all about air circulation.

Edited December 7, 2016 by Estrada

[DGS1244]

One big problem with underfloor cooling is that there is no air filtration. with conventional  A/C you can add HEPA filters which can really improve the air quality essential in parts of Thailand when air pollution is a problem.  

[Naam]

Quote

The benefits of underfloor cooling are similar to those of underfloor heating. It is more cost effective – Thermo-Floor underfloor cooling systems are more cost effective than air conditioning as the outside of the building accumulates less heat therefore reduces heat build up and consequently reduces energy consumption.

absolute rubbish²! because because heat accumulation of the outside walls is neither prevented by underfloor cooling. to arrive at the afore-mentioned conclusion doesn't take any knowledge of thermo physics but only a little logical thinking. commenting on the condensation problem or the uncomfortable feeling of cold floors is already overkill. nothing against floor heating though because that's the optimal heating system for a home where heating is required.

[Naam]

6 hours ago, William C F Pierce said:

It is also possible to have a non-electric dehumidifier if the dew point is of a concern.

you don't seem to have the faintest idea what volume of condensate is drawn out of the air and drained by a single aircon unit when the ambient relative humidity is ~80%.

[autoc]

If it does not exist there might have some reasons why...

[catinthehat]

Anyone here ever seen an "underfloor heating system"? Didn't think so. there are other issues with this.

• The cost of all of the extra kit would be a deal breaker
• With all of that added duct work it wold be a magnet for bacteria and mold (i.e. Legionnaires disease) And would result in the need for major duct cleaning and disinfecting on a regular basis. More cost.
• We use numerous pedestal fans which are much cheaper to run than  air-cons.
• Add to that the above noted moisture issues.

[moe666]

I worked at one of the US national labs for 36 years and in all of my years there they never did any research on in floor cooling yes they did a lot on heating using various methods. Part of the cooling affect is moisture removal by lowering humidity you feel cooler at a higher temp. Other than turning your floor into a wadding pond how will the moisture be removed.

 

I have heard of radiant heat but never radiant cool

[moe666]

1 hour ago, catinthehat said:

Anyone here ever seen an "underfloor heating system"? Didn't think so. there are other issues with this.

• The cost of all of the extra kit would be a deal breaker
• With all of that added duct work it wold be a magnet for bacteria and mold (i.e. Legionnaires disease) And would result in the need for major duct cleaning and disinfecting on a regular basis. More cost.
• We use numerous pedestal fans which are much cheaper to run than  air-cons.
• Add to that the above noted moisture issues.

He plans on using a gycol system with in floor piping no duct work necessary unless he has a cooling tower Legionnaires very doubtful

[khunPer]

Interesting thoughts. But I would not be happy to walk on a floor that cold, that it can cool down the room – mind you, that cold flows downwards, and heat goes up; which makes floor-heating ideal, especially in cold areas where I come from – compared to price of installed modern inverter-type aircons (from around 25k baht = £650) and their low power consumption, I would doubt the benefits of floor-cooling; however, cooling pipes in the ceiling may work.

[Naam]

2 hours ago, catinthehat said:

We use numerous pedestal fans which are much cheaper to run than  air-cons.

you don't say!

[Morakot]

12 hours ago, William C F Pierce said:

 I did mention it should be on an upper floor.  This would allow cold air to fall from the ceiling to create the circulation on the lower floor.

 

 

So are you planing to clue the pipes under the ceiling? Placing them deep into a concrete floor/ceiling will surely have no effect. I still don't get the entire set up! What is the inverter or compressor unit? It sound not very effective running (active) coolant though  concrete unless its right at at the surface. Heating pipes are not "buried" in load-bearing structure; they are placed on top of the floor--often on top of thermal insulation--and then covered with a thin layer of screed. If you want to put cooling pipes in the ceiling, there are no off-the-shelf solutions.

 

 

If you are really interested in alternative solutions, looks for natural ventilation in conjunctions with massive grounds slabs that are cleverly shaded . Possibly even a solar chimney and a ground heat exchanger might work, unless you live in a swamp.

 

Edited December 7, 2016 by Morakot

[Morakot]

Quote

 I have approached a rep of one of these companies in the UK and he thought the adaptation was feasable. 

 

Reminds me a bit of Swiss Toni from the Fastshow; he always promised heaven and earth...

 

 

Edited December 7, 2016 by Morakot

[LindsayB]

Its funny as a hotel owner in a hot as hell place in Summer  West Australia I have always wondered the same question.I do believe it would work.The condensation I am not sure about.If you have ceiling fans you would use them in conjunction with the floor/ ceiling cooling and reverse them with the summer switch that is on them.There are electric pumps that slowly and economically move water (150 watts ) that are used for moving water from roof mounted solar panels to ground mounted storage tanks and for hot water loops even in three storey houses.

I do believe even a drinking water fountain could be adapted to do the chilling but it might need a larger storage tank.As a point of interest but it is a different system Toronto in Canada draws 4 degrees C water from the bottom of Lake Ontario in Summer and uses it to cool about 30 high rise buildings using polyethelene pipe.I do believe they use heat exchangers and still use convection (blowing of air).

[hkt83100]

I hate the idea of getting cold feet.

[William C F Pierce]

14 hours ago, catinthehat said:

Anyone here ever seen an "underfloor heating system"? Didn't think so. there are other issues with this.

• The cost of all of the extra kit would be a deal breaker
• With all of that added duct work it wold be a magnet for bacteria and mold (i.e. Legionnaires disease) And would result in the need for major duct cleaning and disinfecting on a regular basis. More cost.
• We use numerous pedestal fans which are much cheaper to run than  air-cons.
• Add to that the above noted moisture issues.

My own underfloor heating system I installed in the UK consists of overlay boards 600 x 900 x 18 mm with 4 flow and return grooves to take 12 mm pipework in one continuous zig-zag length.  This was then overlaid with tiles. As a cooling system it can take a hardwood overlay in a bedroom as it has a different ambient temperature and not too cold for the feet. If you don't like the running costs of an aircon, it is a possible alternative which I intend to try on having in a new build.

 

Underfloor cooling is gradually coming into use in southern Europe. This is still in the early stage of development and would in time find a suitable version arriving in Thailand. CONDENSATION: The low running cost of a small 6" extractor fan that comes on automatically at a certain humidity level is a viable option. The condensation is greater or less depending on the balance of materials used. Just as you would not have uncontrolled heat in a home. Likewise you would not have uncontrolled cooling  within a given design. If there is a problem look for a solution.

[jacko45k]

On 23/11/2016 at 10:25 PM, Strange said:

So basically you would be cooling the floor itself similar to floor heating? Like the floor and your feet would be cold/hot but its not actually 'heating/cooling' the house? 

 

I might be missing what you are after but if what I said above is true it won't be actually cooling the room IE pulling warm air from the top, across the evaporator and removing humidity and heat in an actual cooling cycle. 

You make a good point for most areas of Thailand where the heat is usually accompanied with high humidity. An underfloor system would not remove the humidity. It may even produce a wet slippery floor, or water dripping from the ceiling, and cause mold.