When will it pay for itself - insulation and double glazing

May I ask if your west wall was rammed earth as well?

My colleague had a architect designed eco-house comprised of 50K worth of rammed earth walls. But they didn't use a radiant barrier on the west side and the sitting room behind it overheats in summer.

What is it sealed with?
Inside and out?
This can greatly affect the thermal cycling.
The wall is the west wall.

Did my colleague's wall 'pay' for itself

Thermal cycling of an uninsulated mass wall is also dependent on diurnal temperature variation. In a desert climate the cold nights 'pull' all the heat accumulated during the day. If the summer nights remain warm you get the same problem as my previous double brick rental after a heat wave - you just get hotter and hotter and hotter

Your Home suggest at least a 8 degree day-night difference for mass walls to work in this situation.

If the wall is getting hotter and hotter then it is likely not dense enough
or doesn't carry enough mass or has been sealed with the wrong materials
negating thermal cycling as we need it.

Before I can comment:

What is the day-night temp difference in your district?

What influence does the wall sealant have on its thermal performance?

The sealant will or won't allow thermal cycling,
the wall needs to breathe (take in and release)
We used a penetrant sealer outside and anti dusting agent
inside.
This was tested by me, yes me, 20 years ago and the proof was in the pudding
Also if the sealant breaks down and allows water entrapment this will detract from thermal cycling too.

Our core business is waterproofing, you can see why we were interested

Our temp range is not so radical being on the cape, since we are about 2ks east from the beach (obviously )
and south east about 40k is the southern ocean, so we are lucky we have the influence of 200 deg's of ocean temps ranging from 15-20c (Leeuwin Current and all).
Our temp here now is about 15 and will fall to about 7, also affected by cloud cover(warmer over night)

I think the latter explanation about waterlogging the wall is more the explanation. The volumetric heat capacity is different between rammed earth and water. Water can hold a lot more heat than brick, concrete or earth before its temperature changes (at least 2-3 x) - and giving it a huge thermal lag. A water wall may need to be only 1/3rd as thick.

See this reference:

http://www.ecospecifier.org/knowledge_b ... 0Materials





The coating itself shouldn't inhibit the release of heat per se. It is too thin have an insulating effect. Heat is released both by convection and by radiation and the coating would have neglible effect.

Its not clear whether you mainly using uninsulated external mass to buffer heat or insulated internal mass to store heating winter.

In a temperature situation there are very cheap materials such as foil sisalation that can reflect the majority of heat trying to enter a building. You don't necessarily need a mass wall. A lightweight envelope is sufficient.

Thermal mass is most cost-effective to place inside the house where the winter sun can heat it, to be later released at night.

I was wanting to know how different your summer day-night temperature difference is.

can be 11-40

That's why your mass wall works well in summer. If it was 35-25 then the night can't pull the heat out fast enough before the next day. People have to be careful in which climate they build a full rammed earth dwelling. This construction would not work well in Cairns.

If you think so.

You have to be careful how you use mass in sub-tropical areas:

That's what the field experience and evidence has shown:

http://www.ornl.gov/sci/roofs+walls/res ... index.html
http://www.yourhome.gov.au/technical/fs49.html

Dyno - I must say I'm a little amazed at your ability to sit there and ask for some data - and then assume that you know how it all works by knowing his day/night temperature differences.

FYI - Once_ Artisans climate zone details are as follows.

http://www.bom.gov.au/climate/averages/tables/cw_009560.shtml

As for knowing what or how his thermal mass works and has been working for him -
You seem to be either ignoring or assuming way to much from your new found passion and "scientific data"

Have you ever been to Margaret River?
Do you know how cold that part of the ocean is?
Or how hot the land gets?

It's a bit like being at Cape DeCoudic (KI) in summer - but with a much larger thermal mass of land around & east of you with much hotter daytime air temperatures.

I've been to both places myself and I've observed the temperatures.
Marg river once in autumn and De Coudic many times in all seasons - many times.

And if designing a house for this climate I would take the following into account first.

How much the land mass affects the temperatures, note the prevailing breezes, surounding terrain, tree types, nearby houses, shading, waterways etc, and only then IMO can one begin to have some the basic data and grounding on where to start, what will work and what won't.

From there you can then start to apply the design principles - but you can't do them as text book implementations / assumptions without understanding the whole picture.

Which I am sure you included as part of your thoughts in your house design.

However - IMO you have failed to do this in some of your above assumptions and posts.

As for thermal mass in the tropics - I'll categorically say YES it can work very effectively.

So long as it is well designed, well shaded and protected from hot breezes - but don't expect the house to perform like an air conditioned house.

Nor is it more uncomfortable than a lightweight house with no mass.

Having lived in the tropics in light elevated tropical houses, and well designed slab on ground houses with wide verandahs, thermal mass and plants all round - both can be very comfortable, but the mass houses can be cooler and more comfortable for a longer period of the year if done correctly and lived in to suit.

I also have friends who owner built a mudbrick house in the tropics which was cool in the wet and dry season. Why ? Becasue the thermal mass walls were 24" thick, the house was properly shaded and the breezes flowed to effectively use the mass, with groundcover and trees nearby to cool to incoming air.

So it is all about what type of house and the temperatures one likes to live in. Which is not text book stuff.

As for the "experts" and "data" knowing what works - like you found out via an email you sent a long time ago to the folks at yourhome - much of this information is for the "standard build" masses -

Not those who know how to design houses that are maximising on the benefits of the material and climate - if they are used in the correct manner.

Here are some houses that rate ZERO on Nathers - yet the owners say they are comfortable to live in.

Why - Because the design is good and the use of materials is used to meet the environment variables properly.

Submission to Productivity Commission Public Enquiry into Energy Efficiency
Energy-Efficiency Standards in Residential Buildings: A Plea for Evidence-Based Policy Making

Dr Terry Williamson
School of Architecture, Landscape Architecture & Urban Design
The University of Adelaide

http://www.pc.gov.au/__data/assets/pdf_file/0019/45109/sub028main.pdf

Steve

Isn't this data supporting the comment I made? If you can't get the temp drop overnight than the external mass doesn't have time to cool down.

And the Your Home reference I provided agrees.....

http://www.yourhome.gov.au/technical/fs49.html


"High humid (tropical) climates
Whilst low mass is generally the best option, recent research has shown that innovative, well insulated and shaded thermal mass designs have been able to lower night time temperatures by 3 to 4°C in high humid areas with modest diurnal ranges."

Warm humid and warm/mild temperate climates

High mass construction is also appropriate but requires sound passive design to avoid overheating in summer.

In multi level/story design, high mass construction should ideally be used on lower levels to stabilise temperatures. Low mass on the upper levels will ensure that, as hot air rises (in convective ventilation), it is not stored in upper level mass as it leaves the building."

YC,

I agree that a highly tailored solution may work equally if not better. However, it does involve a good depth of knowledge. You can also easily make things worse if you don't understand the details. My comments are directed to the masses. Onc Artisan might be able to make things work but if others copy him then without much knowledge they will get the design wrong for their particular situation. If one wants to try a personalised design, it is better understanding the principles of thermodynamics then following a 'recipe'. I feel this is the current problem with 'deemed to satisfy' 5 star building codes - builders blindly following codes so their designs get rubber stamped.

I also appreciate the limitations of home energy rating programs. Our house was rated 5 1/2 stars but it performs better than 8 stars and I don't think we are more resilient than the average person. In fact, my wife prefers to keep the house uncomfortably warm in winter.

I am aware of Terry's submission. I have used that reference before in relation to the impact on occupancy behaviours on household energy consumption patterns.

As my colleague found out when despite the huge investment in mass, it was inadequate to keep the western side of his house cool in summer.

Of the many things that you can use in a house construction, thermal mass materials are the most expensive (unless you are a DIY mudbrick builder). For economical volume building, it would seem wise to extract the best thermal performance for the least investment in mass

Dymo, the major problem is ppl try to stick a lovely house on a piece of dirt and expect it to work.
This is the wrong way to go.
If I were to build you a house, I would be going to site and observing the factors that will
impact positively or negatively over ALL seasons.
Then ask number occupants and series of other questions to evolve a design.
Then I would be consulting with an engineer and other profs to lend their knowlege.
The decor & second fit, is up to you.
Lots of stuff is drawn in an office but will never work on site
The concept of solar passive is in the name.
You don't build west facing windows, orientate 5deg east of due north (solar north)
for mid-lower Australia... Blah blah
chuck the books in the bin and see what work first hand there are plenty of good,
no, great working examples, but you need to get away from what is not working,
to what is working.

As for Yak_chat he gave you examples but you beg to differ,
...solar passive doesn't care what you think, it just is.
Onc_Artisan

I agree. I spent 12 months getting information from the weather bureau, speaking to people in the district, looking at elevations on Google Earth, visiting the site on mornings and afternoons. Building for the site is important.



I presume you are saying this in reference to my build. I pointed slightly west of north as a compromise because of the better views. I would have preferred a more easterly direction. Nevertheless, I don't think it had a huge impact on the house's performance. In free running mode last summer, the interior never got above 28 deg.



So shall I chuck my medical books in the bin and give it a punt? Theory and practice. Practice and theory. They go together hand in hand always refining each other. I despise neither.



I agree with Yak Chat. I agree with a lot of what you say. The Your Home technical guide agrees with everything we have said. Why do you think it is a question of differences.