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Wall thermal mass vs air cond

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Started 1 year ago by johnpao
Latest reply from dymonite69

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johnpao
Member

Hoping to tap into some wisdom with this scenario.

Am designing a very modest house at 72 sq m - going for efficiency/quality over size with this. It's central west nsw - warm to hot summers with cool winters (600 metres elevation)

The house will be on a slab, timber stud walls to outside (with iron cladding) and R3.5 wall insulation and R8 ceiling insulation. Double glazing, large glassed area to north and all glass shaded for summer.

Off the grid - will have a 2kw solar setup.

The house will also have a internal feature water tank (3500 L) that sits behind a slow combustion heater and another smaller (1500 L) slimline tank that is exposed to sunlight thru the north facing doors (probably black with a polished black concrete plinth on top as a feature.)

So ideally in this climate reverse brick veneer walls are the way to go - the mass sits inside this very well insulated skin. Either 200mm filled concrete blockwork or 250mm thick mudbrick.

OK - so the dilemma is: the internal mass walls will cost around $8500 for concrete and $13,000 for mudbrick - so let’s say $10k.

$10k will buy another 2kw of panels - enough to run a high efficiency air cond - using around 1.5kw per hour for the main living area.

A good day in summer with the extra 2kw should give 8-10 kw to run the air cond and give added power for the leaner winter months - could potentially also run a heat pump for the hot water and maybe some revers cycle heating.

Realistically wall thermal mass doesn’t get a lot of sun for winter gain but of course shaded in summer will be ideal - so should I just rely on the slab/water tank mass and go for the extra panels?

Posted Monday 24 May 2010 @ 10:05:26 pm from IP #
dymonite69
Member

Hi Johnpao,

You must be near the plateau of gains for energy efficiency. I would expect that whatever you do from here will have diminishing cost-benefit.

Just a few points

- R8 ceiling is probably over-spec. The improvement in U value is 0.125 W/mK. The relative heat loss via windows and R 2.5 walls will be your weakest point. You may get better absolute heat loss reduction with good thermal curtains or blinds.

- Mass for heat storage works better distributed over a large area rather than one massive section. There is more even and efficient heat absorption this way. Is the extra cost of masonry for internal walls or for an RBV construction? What is your external cladding?

- Mass exposed to direct radiant heat is better at absorbing heat than exposed to just hot air

- You don't want your water container to insulate the body of water

Posted Monday 24 May 2010 @ 11:03:18 pm from IP #
PeterReefman
Member

Wow, 72m2 - well done on that for a start! (got any plans?)

Okay - my take is that you're not doing this for purely financial reasons, so for a start your choice of the reverse BV walls won't be made totally with dollars anyway (good!)

I'm also assuming you don't have any large (or ANY) westerly windows, you don't have any wall to wall carpet on the slab in the solar collection zones, and the house has other good passive features like decent window frames; internal blinds with pelmets; etc.

The short answer in my view is that the extra 2kW coupled with an aircon will blow its doors off, for a number of reasons -
* You already have lots of thermal mass not only in the water tank, but also the slab itself (don't forget to insulate at least the perimeter of the slab).
* You're right the walls won't be helping in winter if you can't get sun on them.
* By the sound of the house you'll go VERY close to not needing aircon anyway, especially if you employ some behaviour aspects like acclimatisation and effective perspiration.
* If you do (NEED aircon) I believe the thermal walls (or lack of) won't be the deciding factor anyway.
* The aircon you've quoted would be FAR more than needed if the house is as well designed/insulated as it sounds. Remember that the aircon simply WON'T be operating at anything like 1.5kW. A small (650w) system in all likelihood would be enough and then only be operating at a third to half capacity, so 1kW or even 0.5kW of extra PV should be enough.

So, in my opinion it's a no-brainer from a bang for buck point of view. Use active systems. But seeing it in the context of the rest of the house, I feel you're looking for confirmation to go the whole hog with the house including internal wall thermal mass. In that case the money argument gets reduced in your bigger picture/vision, and it's really back to being your call.

Perhaps you could go with nothing right now (including the aircon) apart from making the slab ready to take some heavy wall loads and some smart loadbearing points for the roof for an option of an easy retrofit later if need be.

Hope that helps, and all the best.

Posted Monday 24 May 2010 @ 11:11:42 pm from IP #
dymonite69
Member

I did some rough modeling of heating load for a house during a cold winter.

80W/m2 non insulated
50W/m2 ceiling insulated
30W/m2 ceiling wall insulated
25W/m2 all insulated plus double glazing.

Quoted figures for summer is 150W/m2 but this depends greatly on the radiant heat load. It probably would be far less with shaded windows/walls, RFL.

This gives an idea about how to size an AC for this purpose e.g 650W system would give you 2200W of heating/cooling.

However, most temperate areas of Australia have a predominantly heating load

For our cool temperate region. RCAC energy use was 12:1 winter to summer.

Posted Tuesday 25 May 2010 @ 12:19:45 am from IP #
living sustainably
Member

Have you thought about a Trombe wall? http://en.wikipedia.org/wiki/Trombe_wall. I apologise, I am not an expert, I got this from Frateco's post on another thread (http://www.ata.org.au/forums/topic/a-concrete-house-insulation-how#post-44). I don't know who makes them or what they cost, but if you are building new, it sounds like it could be a good option for your Western wall.

Posted Tuesday 25 May 2010 @ 1:00:10 am from IP #
dymonite69
Member

I would only go for an indirect or isolated gain system if I didn't have the option for direct gain. With a Trombe wall, it ends up being another masonry structure that won't form a living space and you need to actively manage it to get useful heat e.g. open and close vents. Your design would already get useful solar gain and storage within the inside of the house.

Judging from your design, your conditioning costs will be already fairly low so anything 'tweaks' will have only a small incremental benefit.

Ceiling fans are always a good supplement for cooling. A wood heater might be a cheaper alternative for heating.

Instead of full RBV what if you just use an internal mass spine running down the E-W axis of the house.

As far as PV goes you could do an energy audit for a year before sizing and installing a system.

Posted Tuesday 25 May 2010 @ 1:23:23 am from IP #
Frateco
Member

Can I ask what the temperatures are through the day and at night for summer & winter?

Posted Tuesday 25 May 2010 @ 1:41:58 am from IP #
johnpao
Member

Great to get this feedback - thanks.

Am thinking of doing a blog on the design, construction and building of this house. Have been inspired by sites like http://tinyhouseblog.com/ - it doesn't take a lot of room to live well and within means.

Have looked at the Trombe wall but decided that it wouldn't fit with our design - but we've positioned a long thin internal water tank as a feature to absorb the sun from the north, similar to the Trombe.

I'm heartened to hear that air con wouldn't take a lot of power to run, especially with all the insulation we will have. The down side is that I find it confuses the body - once you vacate the air con room you perceive it's really hotter than it is.

If we go with thick high thermal mass walls it gives us very deep reveals in our doors & windows (140mm stud frame/50mm gap/200 block) which i really like - it also gives an option of creating a way to really insulate the glass areas with heavy material or design an internal shutter. (whilst double glazing is good I'm still amazed at how much heat is lost thru them).

It's a tough call - I know how pleasant it is to be in a room with protected high thermal mass on hot days - but am attracted to have more power to play with...

Posted Tuesday 25 May 2010 @ 1:42:18 am from IP #
johnpao
Member

Frateco - temperatures for Mudgee during summer average from from 17-30 (lowest last Dec was 7, highest 38) and winter 0-15 (last Aug lowest was -5, highest 25)

(http://www.bom.gov.au/climate/dwo/IDCJDW0200.shtml is great to see daily records for most areas of oz)

Posted Tuesday 25 May 2010 @ 1:51:07 am from IP #
Frateco
Member

Have you looked at hempcrete or hemcrete as your external walls? I am unashamedly going to plug this building material so forgive me all.

Its properties are:
- low thermal conductivity (R value of 4.2 for 300mm thick wall,
- solid mass construction giving good airtightness (you not losing heat or cool through air gaps)
- low thermal diffusivity (slow to change temp once room temp stabilised),
- termite resistant and
- low carbon footprint.

Materials and designs that can create a stable internal temperature, despite the external variations, lead to buildings that require the minimum of heating or cooling, less energy waste and obviously less operating costs.

If you put the aircon on until you have the desired room temp, the hempcrete will maintain that temp easily once you turn the aircon off (low thermal diffusivity).

As opposed to blockwork or concrete, hempcrete has low thermal effusivity - this makes it warm to touch. You will feel warm even tho the heater has been turned down. There is a paper that states, " Sub-conscious feelings of thermal comfort (average between air temperature and wall temperature) are achieved at an air temperature of 1 to 2 degrees lower than in conventional masonry structures. This means that you feel warm even though the heating is turned down, saving hundreds of pounds per year in heating costs."

made from lime and hemp shiv, it can be used as roof, wall and floor insulation creating an esky effect to insulate a building. Hempcrete's insulating effects come from its aerated and cellular matrix. It can be finished with render or you can batten it and have your iron cladding with an air gap to release the hot air and allow it to breathe.

It's natural, recyclable and it does not require specialist trade. And yes, we sell it.

Posted Tuesday 25 May 2010 @ 2:24:27 am from IP #
johnpao
Member

Happy to take a look - do you have a website?

Thanks

Posted Tuesday 25 May 2010 @ 2:28:54 am from IP #
Frateco
Member

http://iprojects.com.au/portal/content/view/30/111/

At the moment, trying to establish a new "hempcrete only" site but this to start. What I can offer tho is any tech docs you want and research papers that can help. I'll need to email you them tho.

try me at davide.m@iprojects.com.au if you want or call 0438 006 059.

Posted Tuesday 25 May 2010 @ 2:35:05 am from IP #
Frateco
Member

You can also look to the UK site where they have done heaps of research on hempcrete.

http://www.limetechnology.co.uk/

Posted Tuesday 25 May 2010 @ 2:58:15 am from IP #
dymonite69
Member

Hempcrete shares thermal properties with some other materials. It has intermediate mass and insulation properties like Timbercrete, AAC and log cabins.

The BCA has approved single skin 200mm AAC (without additional insulation) for temperate climates.

Your observation about rapid changes in temperature agrees with thermal comfort research. Our bodies adapt better with smaller variations.

If I work outside in the cold for a while, the house seems overheated for comfort.

Many houses fluctuate dramatically over the diurnal cycle and exacerbate the feeling of discomfort (and provoke a requirement to artificially condition the environment).

Posted Tuesday 25 May 2010 @ 3:11:51 am from IP #
Frateco
Member

It's actually better than AAC in performance ut is very close to wood.

Timbercrete is more dense as is AAC and therefore does transfer the heat quicker tho.

Saying that, these products do work well.

Posted Tuesday 25 May 2010 @ 4:10:13 am from IP #
Frateco
Member

"It has intermediate mass and insulation properties like Timbercrete, AAC and log cabins."

No, it has better insulation U value than Timbercrete and AAC.

Hebel 250mm thick has a dry state R value of 2.15 (CSR HEBEL TECHNICAL MANUAL).
Hempcrete wall 250mm thick R value of 3.6.

Timbercrete has a thermal conductivity value of 0.314. (http://www.timbercrete.com.au/test-report-summary.pdf)
Hempcrete has a thermal conductivity value of 0.07. (http://www.limetechnology.co.uk/upload/documents/Hemcrete/Hemcrete%20U%20Value%20datasheet_H0709.v2.pdf)

AAC has a thermal lag time of 8 hours, hempcrete 15-16 hours.

Wood tho has slightly better values than hempcrete.

Posted Tuesday 25 May 2010 @ 4:42:43 am from IP #
cool at home
Member

Johnpao, I'm not an expert on windows - and I'm sure someone reading this will be - but just in case your reference to 'shading' all windows meant tinting/toning them, I wanted to say that is not wise on all elevations.

Toned/tinted windows dramatically reduce visibility within the home (and leads to overuse of lights... which are hot!) and reduce the effectiveness of winter sun on the northern elevation. Double glazing GREAT, but not tinted/toned all round the house.

Now if 'shading' meant awnings, particularly retractable ones, well that is grand!

Posted Tuesday 25 May 2010 @ 1:42:46 pm from IP #
swanning_it
Member

Frateco, down to brass tacks I guess! Is Hempcrete cost effective?

Could you also explain the wall a bit for me please? Like is it interior, exterior or single skin? How do you run services and how do you support the roof or additional floors? What's the finish, render? Is it suitable to use as a dividing fence and is it poured, layed or what?

Sorry for the barage, I'd just like to understand the concept a bit better. Also, does it meet council requirements in Qld?

Posted Tuesday 25 May 2010 @ 9:35:39 pm from IP #
Benny
Member

Wow - I thought thermal analysis was complicated enough and now we have 2 new terms "thermal effusivity" and diffusivity. From what I read ..
"effusivity is a measure of its ability to exchange thermal energy with its surroundings" - so for a thermal store wall, we'd want high effusivity - right ?
And
"Substances with high thermal diffusivity rapidly adjust their temperature to that of their surroundings, because they conduct heat quickly in comparison to their volumetric heat capacity or 'thermal bulk'". So again we'd want high diffusivity for thermal store walls.
Although for external, insulating walls we'd want low effusivity and diffusivity - right ?
Bugger, I think I'll just stick to heat capacity and conductivity/R value.

Johnpao - I think the idea to spend the money on an "active" option sounds better. If your added thermal mass - especially internal - doesn't get cheap (free) thermal input, then you have to add energy to warm up that mass as well as the internal air (and contents). The lower the internal mass (heat capacity) the less energy you need to warm up the environment. If you do have free energy input - ie N glazing and dark slab floors, then adding internal thermal mass is a good idea, but if you don't then it doesn't really help you. OK it smooths out temp variations, but you have to put the energy in to heat it up in the first place. Just ask people who have old, dark houses with lots of internal brick walls - like we do - once they are cold it takes heaps of heating to get them warm again.
And take note of dymonites point - typically Aust houses use far more energy for heating than for cooling.

Posted Wednesday 26 May 2010 @ 1:40:21 am from IP #
Frateco
Member

Okay this could be long winded but hopefully I can get the picture for you all.

Firstly for clarity, hempcrete is a generic term for an old basic recipe of lime, hemp & water that has been used for decades in Europe for the restoration of old wattle & daub or cob construction. Have a look at "Tom Woolley - Hemp lime construction. A guide to building with hemp lime composites". Unlike concrete or masonary, hempcrete does not crack severely under movement. Lime is weak under tension and develops micro cracks under movement that heal when it gets moisture. Concrete or masonary will let go suddenly under movement which is why you get big noticeable cracks.

Tradical Hemcrete is a hempcrete mix using a proprietary lime binder Tradical HB with hemp chips that has commercially-defined properties and British certification. This is what I am promoting. Hempcrete can be used but its properties are not commercially "proven" which is harder to get passed. Having shown building certifiers, they don't have a problem under the "Deemed To Satisfy" provision of the BCA. We have just had a building certifier approve for construction a house in Tasmania - the energy efficiency auditor using AccuRate gave it a 6.4 star rating and apologised cause the software wasn't good enough to achieve higher in Climate 7 region. He felt we could get 7 star with a more complicated commercial software that could better accommodate some of the beneficial properties such as airtightness(depending obviously on glazing used).

So how do we use hemcrete? This is monolithic construction - solid wall. Hemcrete is not runny like concrete - the best description I've heard is that it's like elephant s##t, you have to squeeze it hard to get water to run out. So it's damp but not wet therefore most machinery like concrete pumps cannot work it because lime sticks to anything and blocks too quickly. It can be made into blocks although it increases costs and embodied energy dramatically, does not provide as good airtightness and will be a more dense mix thereby not providing the best insulation values.

Hemcrete is deemed non-structural although it has small loadbearing capacity. Therefore you build a frame (preference is for timber - no thermal bridging) to do the structural work ie the backbone. Services are then positioned as normal. You shutter approx. 1.2m up around the entire wall frame - the shutters can be 6-9mm ply since there is no hydrostatic pressure on it. The thickness is solely to keep it straight. If you frame the shutters at 450mm centres, you can use 4mm ply (it does work!).

"Pour" the hemcrete in and encase the frame. Imagine a BV house frame - remove the BV and replace the entire space with hemcrete to 250mm (you don't need the void), that's what it would look like. After a day's pour, next morning you strip the shutter and go 1.2m up and do it again. Hemcrete will not slump.

The frame can be located to one side of the shutter for ease of fixings or centrally located in a 250-300mm wall to allow services along the frame rather than through it.

Right now, the proven method to 'pour' hemcrete is by bucket! Now before you go nuts, hemcrete is about 1/8th the weight of concrete at 330 kg/m3 therefore a wheelbarrow load weighs no more than 15 kg and a 15L bucket only 5 kg. You'd be amazed how much you can get done since it's light to work with. When you pour it, you lightly tamp to give it structure into joints and around the timber.

Hemcrete needs to breathe (vapour-permeable) to perform well in damping humidity and temperature. You can render it with a lime render externally or batten it so that there is an air gap between the non-breathable cladding and the hemcrete. No need for sislation. We are looking to use a breathable (vapour-permeable) board like Magnesium panel to internally line the walls therefore achieving a breathable skin that can look like normal finishes. Mag board can be used externally as well. The paint needs to be vapour permeable as well.

We have a 1m high x 1.4m long x 250 thick wall that has been outdoors unfinished for 21/2 years now - there is no mould, it has bleached and has not degraded so it is durable.

Last but no less important, cost-effectiveness. It is cheaper than Hebel blocks - taking into account timber framing, it probably works out around the same price but the performance is far superior. Right now, we are prototype testing a high volume sprayer that will make hemcrete a very viable commercial product for large and small scale projects. Until this has been fully developed, I believe hemcrete best suits owners, owner-builders and builders that place thermal performance above low cost such as people in this forum.

As a fence, you could put it up without a finish. I would make it really dense tho to handle any impacts. Mind you, if it gets damaged, you scoop up the damaged pieces add a bit of binder and re-use it to repair. No waste, totally recycleable.

I am based in Brisbane so if you want to chat call me on 07 3324 9770 or 0438 006 059. Just ask for Davide.

Posted Wednesday 26 May 2010 @ 2:03:50 am from IP #
Frateco
Member

Benny, your statement is not strictly correct - "The lower the internal mass (heat capacity) the less energy you need to warm up the environment". Less energy is used to heat up the internal mass but then that internal mass loses its energy quickly thereby needing constant energy to keep it in a steady state. Ideally what you want is a mass that absorbs the heat quickly and retains it for long periods thereby achieving dampened temperature fluctuations.

"OK it smooths out temp variations, but you have to put the energy in to heat it up in the first place. " Radiant heat from the thermal mass generally is not sufficient to heat a place if it's cold. What it will do tho is allow the place heat up quicker and maintain that heat so you still need to put out energy to heat it up, just not as much. You just don't want to have the heat up constantly to keep it comfortable.

Posted Wednesday 26 May 2010 @ 2:13:06 am from IP #
Benny
Member

Thanks for the big explanation of Hemcrete Frateco - it sounds interesting.

I don't agree with you on the thermal analysis though. I'm talking about a building with 2 options, no extra internal mass (heat storage wall etc) or a large thermal mass. Both options with exactly the same external skin/insulation. To achieve a given internal temperature in the building, steady state, including the thermal storage mass at the same temperature, you will need to put in more energy for the building with the thermal storage. Or for a given power heating source, it will take longer to heat it up as you have to heat up the air and the thermal mass.

Once its all heated up, the steady state energy requirement will be the same for both options, as that is determined by the skin/external insulation of the building - nothing to do with "internal" thermal mass.

Posted Wednesday 26 May 2010 @ 7:03:25 am from IP #
dymonite69
Member

A few misconceptions about thermal mass mentioned so far. I wish to clarify.

Thermal mass has high volumetric heat capacity (requires large amounts of energy to heat it up) and intermediate thermal conductivity (less than metals, higher than insulation).

The rate of net heat transfer into and out of the mass is also governed by the mode of transfer (radiant, conductive, convective) and the surrounding conditions (air temperature, presence of line-of-sight radiant sources).

When applied in building, radiation is usually the main process of heating. At night time, conductive/convective loss occurs in response to falling ambient temperatures. For a temperate climate you want this to occur internally (hence internal mass). For a hot, arid climate you want this to occur externally (hence massive external mass).

Mass is controversially used in a hot, humid climate where it always sits in shade and absorbs and releases heat by convection - thus buffering temperatures. Ideally you need high rates of night time ventilation to achieve this.

Mass is therefore a storage battery of thermal energy. If there is too much mass (and not enough solar gain) it can act as a perpetual heat sink in a cold climate. If mass is exposed to too much radiant heat, it will be a continue (uncomfortable) heat source in a hot climate.

Posted Wednesday 26 May 2010 @ 8:03:00 am from IP #
Eco
Member

Johnpao

You have a large amount of thermal mass in the water tank. Does the large water tank just sit inside the housing envelop or are you planning to somehow heat or cool the water in the tank? If it is just passively sitting there I would be concerned about how quickly you could get room heat into the water to enable you to get the full value out of the tank in summer.

Have you considered placing hydronic tubing into the slab to allow the possibility of pumping the water through the slab to cool the slab and get the coolness out of the water tank more quickly - probably would only need to use it on the hottest of days. It will also open up the possibility of radiant cooling overnight - dymonite knows all about that. (I don't think you need more thermal mass - not $10K worth anyway. And you won't have cut out the possibility of latter installing the PV and RC aircon.)

Looking at your temperature data in January the average is around 23.2 degrees (averaging mean max and min temp) so I would anticipate that your water tank (and house) would also fluctuate around this temp in January. The water tank by itself (not considering radiant cooling at this stage) would not cool substantially below this temp. The house could well go into the higher twenties during hot days. That is quiet warm (for me)so to live with those temperatures you would have to have things such as ceiling fans. (Otherwise RC aircon and PV might be a solution.)

Posted Wednesday 26 May 2010 @ 8:53:11 am from IP #
Eco
Member

One other thought. There is a downside to thermal mass in warm climates. That is that overnight it will tend to try to keep the temperature inside the house higher than the now dropping temperatures outside. So you say the outside average minimum temperature overnight in January is 17 which is a nice sleeping temperature. However the thermal mass in your house would not have cooled down that much and would tend to be trying to keep the internal temperature higher than this. Perhaps not desirable unless you like warm sleeping temperatures. Need to have lots of night ventilation and perhaps less mass in sleeping areas.

Posted Wednesday 26 May 2010 @ 10:18:29 am from IP #
johnpao
Member

Thanks Eco. The tanks are static, although the north facing tank will get direct sun for a solid couple of hours in winter and the large tank will get the heat from a slow combustion heater in front of it. Just looking now into a wetback to heat the large tank which may be the way to go - probably no issue of it getting too hot with 3500L and could help with the risk of the fire overheating the space (it will be a small Nectre - we had one in our last house and the heat was amazing from such a small heater). Have to find out if a steel tank can be heated like this of course - might melt the aquaplate lining.

Looking into the possibility of running 100mm pipe under the slab with a fan to help cool the air during summer - there has been some talk in this forum but looks like the jury is still out this.

I was hoping if we go with the mass walls, being coupled directly to the slab and protected from the sun would cool down fairly overnight?

So at this stage winter is looking pretty much OK without the mass walls, relying on the insulation, good north sun and mass of slab and internal tanks.

Posted Wednesday 26 May 2010 @ 10:43:00 am from IP #
Eco
Member

In summer the more mass the more the internal temperature will tend to stay closer to the average temperature. More mass would not cool down quicker - quite the opposite.

Posted Wednesday 26 May 2010 @ 10:56:31 am from IP #
GBD
Member

Johnpao,

Back to the Solar systems as mentioned in your first post.

Are you running off grid?

So does the possible air con need run off batteries?

Have you done some calcs on A/C power drain, solar inputs in winter and a/c run times?

I suspect the figures may not stack up as being very viable if you are off grid.

I've lived on an 6.5kw system in northern oz (much longer sun hours than Mudgee) and even doing tasks like a load of washing needed to be co-ordinated to with a good solar gain day around midday to ensure battery life was maintained for their longer term life.

Posted Wednesday 26 May 2010 @ 1:47:30 pm from IP #
hasdrubal
Member

Have you considered using Strawbales for the walls. They effectively super insulated with claimed R ratings between 5.5 to 8.5 depending on bale thickness etc.

The other advantages are its environmentally friendly, relatively cheap and can be built using unskilled labour.

I haven't built with it myself but did a workshop a few years back. There is more information in the following link (and there are books available as well).

http://www.strawtec.com.au/page.php?id=1

Posted Thursday 27 May 2010 @ 8:33:01 am from IP #
Russell Moore
Member

johnpao, is this house for you to live in, if so what will become of your lovely tilt adjustable PV set up at your present home?

What others are saying about internal thermal mass staying warm overnight in summer is correct. What you will need is some way to get as much cooler night air into the house as possible, whether this is by fans, or natural air flow is the real question.

My house's internal temp' can get up to 28c in summer, with outside temp's of 40c, but early in the morning, internal temp's may have dropped to around 22c, while the outside temp' is in the high teens.

Clever use of correctly placed windows and doors helps a lot, but some kind of fan forced air flow will be even better, especially on nights when there is very little wind. I just use a pedastal fan placed in a shroud at an open door to draw air out of the house at night, but I see on other threads here that some form of all house fans may be the way to go.

Posted Thursday 27 May 2010 @ 12:27:43 pm from IP #

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