Can a timber frame house be energy efficient in zone 7 (Victoria)?

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Can a timber frame house be energy efficient in zone 7 (Victoria)?

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Started 4 years ago by VinceMD
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VinceMD
Member

Hi,

I've been renting investment type property (single glaze) as well as old houses (leaks everywhere) in East Gippsland. We are cold in winter and over it. My partner is sensitive to cold. And we are both sensitive to energy bills and impact on the environment.

The good news: we are building!!

We found a builder that builds prefab houses which are transported to the site. They look stunning, better than most houses in our suburb. Modern look, great floor plans, open spaces. The build are timber framed based with batt insulation. They comply with 6 star rating. However I understand the rating is projected and not the actual since it's measured via a computer software.
Their inclusion for R rating is 2 for walls and 4 for walls. But they say this can be increased.

I've read the "Design For Climate" http://www.yourhome.gov.au/passive-design/design-climate
And I've done a fair bit of reading on passive houses.

Our block of land is huge and I have the opportunity to maximise glazing north and avoid east and west glazing as per government's recommendation.

While passive house is too expensive, can I still achieve energy efficiency and great comfort with:

- ask the builder to increase wall and ceiling insulation as they offer it. I don't know the cost. How much rating should I get for zone 7?
- Sanden heat pump for hot water
- dry floor heating (can't have slab heating as this is transportable home so as dry suspended floor). A dry floor heating: http://univenta.com.au/product/dry-floor-heating/. Alternatively radiator/panels if floor heating falls through
- heat pump to feed the hydronic floor heating
- double glaze thermally broken windows everywhere
- energy efficient fire heater for the look and the very cold days and if can get cheap wood
- external permanent shading for summer

What else can I ask? How can I be sure the house is not leaking? Can I get someone external to audit or should I just trust them?
Am I on the right track? Does this have the potential to provide a comfortable cost effective house? Or is it not going to happen with timber frame at all. Unfortunately not much thermal mass as there is just no concrete/brick in this build.

The cost of the house is less than $2,000 per square meter with this prefab builder. As they build in factory, their cost are pretty good.
I looked at SIP panel based builder tells me cost will be near $3,000 per square meter. It just blows the budget and I doubt I'll get my money back with loan interest and so forth.

What is your opinion?

Posted Tuesday 16 May 2017 @ 11:19:42 am from IP #
d.darroch
Member

No, a timber framed home won't be as tight as a SIP home. But don't freak out too much, timber framed homes can be energy efficient. Just look at Scandinavia, very cold climate, majority of homes are timber framed & very energy efficient. Generally a prefab build should be more tight than a stick frame built on site, as tolerances should be smaller, & they should follow best practice, unlike some chippies on site. But I'd definitely investigate the construction system your prefab builder uses, what wall wraps they use (breathable), how to they minimise thermal bridging? I'm no expert, but I'd definitely be reading up on timber framing techniques. Maximise you insulation in the ceiling & walls, generally doesn't cost a lot. Also don't forget about underfloor insulation, important in your climate.

Yeah, internal thermal mass will be the challenge for you. But remember the thermal mass must be inside the building envelope, protected from the elements. So a brick veneer house may not be any better than a light weight clad house anyway. The mass must also have access to sunshine. A double brick home may be not be any better if the thermal mass doesn't receive sunlight.

Looks like you've been researching flooring systems, trying to get some thermal mass in there. Would be nice to get some mass in the part of the floor that receives sunshine. I'd push this point, see if they can come up with anything. Any chance of a screed, or too heavy? Water has extremely high thermal mass, so your hydronic system will have some thermal mass. Would be nice to have it in the sun though, & more of it. Other options? Tiles will add a bit. A large fish tank? Phase change materials (though they're expensive)?

Posted Wednesday 17 May 2017 @ 8:51:14 am from IP #
VinceMD
Member

thanks, that is reassuring. I've been in touch with Anchor Home: http://anchorhomes.com.au . I'm trying to fetch more details around the materials and technics used. And if I can get third party to install fancy things like heated subfloor, etc

As a point of comparison a SIP panel bespoke design company is charging $200K more for the same size. They are saying they are more expensive because they don't have set products and it's all bespoke. So to truly compared I would need to find a SIP company that does set products. A unicorn.

I'm chasing info from Anchor to see how good we can make the insulation.

It's good to hear a prefab build can be of higher quality.

I'm not sure screed or any other thermal mass can be added due to the weight. Phase change materials: very expensive! or maybe just cover the wall the most exposed to sunlight. Not sure if that would be useful or a complete waste

Posted Thursday 18 May 2017 @ 3:39:22 am from IP #
Canberra Mark
Member

Up the wall and ceiling insulation (best bang for buck). Does the pre-fab come with sub floor insulation as well? Make sure it does. Personally i'd avoid hydronic heating in a lightweight constructed building- some efficient reverse cycle air cons could handle heating/cooling no sweat. Ensure your northern glazing has a suitable eave to restrict unwanted summer ingress. Pelmets, honeycomb curtains, avoid downlights, choosing the right extractor fans will all help. Put in services so you can offset your consumption with rooftop PV. Because it is prefab- a fair bit of the building tightness will come down to the on-site side of things. If you can get your builder to pay extra attention to building envelope tightness you can make significant gains with nothing more that 20 tubes of caulk, and a few rolls of tape.

Mark

Posted Friday 19 May 2017 @ 11:21:42 am from IP #
VinceMD
Member

Mark, a lot of new words to learn for me but very useful. Appreciated.

I've asked the builder for their energy efficiency options. They will give me a quote for:
- air-cell insulation to walls
- roof blanket and 6.0 batts to the ceiling (instead of 4)

Currently there is R 1.5 under floor insulation. No upgrade option here. I wonder if we can add insulation under the house since the house will seat on columns above the ground (but with a skirt around it for the look and avoid cool air moving too much in winter).

I have asthma, allergy and I'm from France, so very much used to the comfort of hydronic.
First quote I got was $36K (could heat the house and a pool, probably over engineered). Second I got is $17K based on radiator panels and a 12KW Immergas pump. But no buffer tank, which is interesting (not required with this pump as it's a complete system itself, I've been told). Here is the product: https://www.huntheat.com.au/products/heat-pump/immergas-audax-12/
I'm a bit concerned about the noise though... 67DB.

I'm waiting to hear back from hydronic through dry suspended floor supplier for a quote. The guy who quoted me for radiator and pump does not think this type of floor heating works. And he mentioned than even if I had a slab, it would take hours to warm up. Not very reactive.

Said that I'm planning to get a wood heater. For the style, the ambiance and we can get access to firewood. So it could be that I wait for the hydronic and just use firewood the first year, see how I go, save some money and decide which way to go depending on the energy we need.

The eave on the north side for the summer is something I'll have to bring up. The builder has them on their latest design. They have energy consultant so hoping we can work that out. My previous house had lot of windows, lot of light. Great in winter. A disaster in summer. I'm not doing that again! External shading is required. Overall, living in East Gippsland, there aren't too many hot days. It's a very temporary discomfort and we will have ceiling fans in every room (reversible for winter).

To be honest I haven't even thought about curtains yet. In Europe I found them very useful. In my rentals in Australia, it's been all crappy, too light, not the right size, breaking, etc. I've never been happy about how curtains look in general. I guess I will do some research.

Mark, what is the issue with downlights? I'm not a big fan but don't mind them too much. Is it an issue with leak they could create? Builders has an option for LED downlights but expensive.. What would you suggest? What about light integrated in the ceiling fans?

Re envelope tightness, a bit of a gamble. I will bring it up, see how they react. Probably once I'm past the sale stage.

PV: kind of running out of cash here. Maybe a good idea to observe the consumption for the first year to size the system right? Or is it never a good idea to wait for PV since I would be wasting money on electricity bill?

Posted Friday 19 May 2017 @ 2:08:11 pm from IP #
Canberra Mark
Member

Given you have the luxury of building new I would give significant thought to going all electric and not using gas. The gas market in Australia is pushing up prices, and the industry as a whole is orchestrating shortages to get governments to look at more environmentally risky extraction options such as fracking which threatens agriculture, clean water etc. You can skip the inevitable rising prices, and connection costs by simply choosing not to use it as a fuel source for your house. Induction cooktops are super efficient, really fast, and easy to clean (not to mention safer), heat pumps can do your water and space heating/cooling. By going all electric you also make the most of any future PV installation you put on your house/property as you are able to maximize self consumption.

Downlights are bad because you are essentially punching holes in what would otherwise be a very efficiently sealed insulated cavity. Use LED track lights- much more versatile (can be oriented to light up artwork, work spaces etc) and doesn't affect your ceiling performance so much.

For the sub floor insulation- the R1.5 extruded foam is only about 40mm thick. I'd see what it would cost to use a 2.0 or higher foam. You'd only be paying for the added material cost- the labour would be identical. Easier to do in the factory than later on site.

mark

Posted Saturday 20 May 2017 @ 4:43:56 am from IP #
jdaley
Member

I would suggest looking at Rocket mass heaters, coming from France you may know then as Russian Stoves.
I live in a wilderness area and I don't use curtains for privacy, so you may not need them with what you are planning and the money saved could be put somewhere else.
Pool heating sounds over the top?
You may be able to install bricks as part of walls, as thermal mass.
A good wood heater, with thermal mass near it, a good supply of wood, a wet back and some water radiators in the back rooms may be sufficient.
As for leaks, it is possible to do a test for air leaks, just google it for the procedure.

Posted Thursday 22 Jun 2017 @ 11:17:46 pm from IP #
Morbo
Member

go double glazing. Insulate everything. Make it alllight colours. For some extra mass you can use soundcheck plasterboard, its twice as dense as normal plasterboard. Ormaybe FCsheet, does not break that easily. Heavy curtains and sunblinds. Get orientation right. Our renovated weatherboard outperforms colleagues brick veneers.

Posted Friday 23 Jun 2017 @ 12:19:13 pm from IP #
jdaley
Member

Fibre Cement sheets

Posted Saturday 24 Jun 2017 @ 12:11:29 am from IP #
VinceMD
Member

thanks for the input. My problem is to find a builder that is onboard with all this and can serve East Gippsland.

Posted Saturday 24 Jun 2017 @ 9:00:58 am from IP #
Morbo
Member

why builderif its prefab?
I also would suggest, don't be stingy with stumps, if its on stumps. Or is it on a slab?

Posted Saturday 24 Jun 2017 @ 11:09:40 am from IP #
VinceMD
Member

When I say builder, I refer to the company building it in factory and transporting it to the site. To me, prefab simply means most of the work is done off site, in a controlled environment (warehouse).
So there is a company that takes care of everything: from initial land inspection all the way to connection to services.
But if there is another way to go about it, I'll be interested to learn

It would be on stump. The company I contacted said they use concrete stumps and simply "drop" the house on it. Then they just assemble the modules (3 modules for a 4 bedroom house) and do the finishing so it looks like it came in one piece (+ connection to water/electricity etc)
Why not stingy on stumps?

Posted Saturday 24 Jun 2017 @ 1:33:39 pm from IP #
Morbo
Member

in some parts of our house they are 1.6m apart, a bit bouncy. Plus some may set to a different level than others. I put anextra one in for the washing machine and one each corner of the bathtub. Having seen a gap in the silicone each time you step in the bathtub at a friends I was a bit worried.
Plus If I was to build from scratch, I wouls make sure its dry around the house for at leaste 1 m. Out front door goes out of whack by 5 mm depending on I don't know what. Some years its level some not.
Plus they cast the driveway on top of the ground level, so the house is in a dip. Water gets in and takes forever to dry up again.

Posted Saturday 24 Jun 2017 @ 10:35:58 pm from IP #
Eco
Member

There are surface mounted LEDs now. I went for a central batten fix light with an LED globe - old fashioned but it works. Consider ceiling fans for living rooms.

I agree that hydronic is a nice form of heating - but you pay for it. Have you considered using multi head reverse cycle air conditioning. Probably cheaper - worth pricing it anyway. And with the savings you might be able to buy a PV system and batteries to provide the energy to run the system - at least in part. The AC system would also provide cooling in summer - most hydronics don't. Cooling may be more of an issue with a low mass house - though as you say you might not get as many hot days where you live.

It a matter of choice - hydronics - a nice form of heat. AC still does the job but some air movement and low level noise.

Posted Sunday 25 Jun 2017 @ 1:28:20 am from IP #
Morbo
Member

I heard Bunnings does timber frames? Why not just get the frame pre-made and then do anyting eles as usual? Then you can select tradies.

Posted Sunday 25 Jun 2017 @ 8:53:41 am from IP #
VinceMD
Member

I'm not a owner builder though. I'm not sure I would know how to handle this project. First time looking into those things.

Posted Sunday 25 Jun 2017 @ 11:40:51 am from IP #
Morbo
Member

you grow with your tasks.
No idea if its better getting the frame made in the big smoke, there used to be a prefab place next to work, I think they moved a few corners. Prebuilt dot com dot au. Maybe they are a bit more open to out of the ordinary projects.
Wejust interviewes a lot of tradies for each job. Essentially rebuilt the whole place, would have been easier to start from scratch.

Posted Wednesday 28 Jun 2017 @ 11:53:55 am from IP #
KayKay
Member

Hey Morbo, we must be neighbours, I am down the road and round the corner from both Prebuilt and Anchor Homes!

Last year I did a rough build cost per square metre comparison of various prefab builders, with a sticks-and-weatherboard traditional builder (Country Lane Homes) thrown in. My results were:

Prebuilt: $2,360 to $2,590
Anchor: $1,259 to $2,637 (although most of the range was well and truly less than $1,700)
Archiblox: $2,380 to $3,189 (though the Carbon Positive range was $5,079 to $5,396)
Ecoliv: $2,750 to $2,984
Country Lane Homes: $1,384 to $1,560

Note this is just the build cost of their standard offerings as described in the various companies’ literature. It doesn’t necessarily take into account other costs like obtaining planning and building permission, crane or truck hire, utility connection costs and so on.

Personally I love prefab houses and have a minor obsession with them, but can’t understand why they always come up costing more to build. Is it just that most manufacturers have to pay for lease of their factories, as well the power, site office, worker conveniences and so on? Obviously in a traditional build, there is no cost to the builder for the land on which they work (absorbed by the owner), nor indeed for the power, loos and so on (also met by the owner but not costed into build costs per square metre).

Posted Sunday 16 Jul 2017 @ 12:28:16 am from IP #
simgue
Member

Really interesting thread, I was going to ask whether you'd checked out the ecoliv guys in Wonthaggi. Went down to Cape Patterson the other week and had a look at the new development they're doing down there with companies like Sociable Weaver, Ecoliv etc. I love their houses and want to go down the prefab route but am often left wondering why the cost is so high for what comes as standard.

Posted Sunday 16 Jul 2017 @ 12:17:18 pm from IP #
VinceMD
Member

Same. All too expensive apart from Anchor. I came back to Anchor on Saturday to look at an août finish Hampton 16.
We are very close to signing with them. Lot of good stuff in the houses we saw.
But I want to keep a close eye on energy efficiency. I have to find a solution t block the sun in summer. Original design does not have eaves big enough

Posted Sunday 16 Jul 2017 @ 7:47:31 pm from IP #
VinceMD
Member

There is also Clifton mobile home near Bairnsdale . Their website is outdated but they seem to do similar thing to Anchor and similar price.

We got in touch with Kithome too, but they are not technically a builder. They provide the house flat packed. Also affordable.

Posted Sunday 16 Jul 2017 @ 8:12:45 pm from IP #
d.darroch
Member

VinceMD said:
I came back to Anchor on Saturday to look at an août finish Hampton 16.
We are very close to signing with them. Lot of good stuff in the houses we saw.
But I want to keep a close eye on energy efficiency. I have to find a solution t block the sun in summer. Original design does not have eaves big enough

I really like the style of the Hampton too. How wide are the eaves on the living room section? Looks like around a metre, which I'd guess should nearly be enough to shade most of the glass doors in summer. You could attach an extendable horizontal awning under the eave, to extend the shade further. Just extend it when required. That's what we have here.

The problem is all the other windows, with no eaves at all to shade the sun. You could look to have your builder add louvered fixed awning sunshades above the other windows. Plenty of manufacturers & designs to choose from, either metal or wood. I think these give an architectural look that is appropriate to the Hampton. Something like this,

http://www.spec-net.com.au/press/0208/aad_200208.htm

If you're walls won't be shaded by eaves, they'll receive a lot of direct sunlight. So it's definitely a good idea to use aircell in your walls, or some other type of reflective insulation (with the appropriate air gap).

Do you have any scope to rearrange the Hampton 16? It looks OK for passive solar, but not great. The N/S windows living area would be great for cross ventilation in summer. But for winter it would be better to have more of the living area facing north, say, the dining area on the north & bed 3 on the south. If that's not possible, is it at least possible to rearrange the windows (I think you said above that you'd aim to do this)? If so, I'd greatly reduce the size of the S facing dining & kitchen windows. Along with obviously removing the W window in Bed 2 (& reduce the S window), I'd reduce the E window in bed 1, & maybe add a N window here.

Posted Monday 17 Jul 2017 @ 7:12:50 am from IP #
VinceMD
Member

We should probably create another discussion thread, but...
So we are going for Hampton 19, which is just longer with 1 more bedroom in between 3 and 2.

d.darroch said:
I really like the style of the Hampton too. How wide are the eaves on the living room section?

I think you are about right. Probably 90cm.
The Hampton 16 we visited, the owner had decided to remove the eave on the North side and make the living room bigger. It's possible that they wanted another orientation for the house too. I think their S was their North.

d.darroch said:
You could look to have your builder add louvered fixed awning sunshades above the other windows

Yes I'm thinking the same. And thanks for the idea. I'm not good with style, so if you see more louvered that could look good on the Hampton, let me know. Note that the Hampton can be built with split skillion roof/facade, which might help with having small eaves all around. I've checked with them. It could be slightly cheaper on split slillion facade.
I like Cube facade more but I'm open. Could even do half/half.

If I decide to not have eaves on north side (like the one I saw) in order to get a bigger living room, I'll have to use a long louvered on the north side above the living room stacker doors. Again, need to check it will work with the style... I assume we can't make the living room deeper AND have eaves because the module needs to fit on the truck and on the road.

d.darroch said:
If you're walls won't be shaded by eaves, they'll receive a lot of direct sunlight. So it's definitely a good idea to use aircell in your walls, or some other type of reflective insulation (with the appropriate air gap).

They can do air-cell insulation to walls, roof blanket and 6.0 batts to the ceiling. That's up to the client, as long as it fits in walls/ceiling, etc

Default inclusion comes with:

- R 4.0 ceiling insulation batts
- R 2.0 wall insulation batts
- R 1.5 under floor insulation
- simple glaze windows (we will go for double or thermally broken, depending on benefits and prices of the latest)

d.darroch said:Do you have any scope to rearrange the Hampton 16?

Yes.
What you can easily do is flip the house. You can have bedroom 1 on the East and the others on the West. Or you cam make the south, become the north (that's just position)
Internal walls can be changed too as well as rearrange the windows. But basically with Hampton 16, I believe you have 2 long big modules (2 trucks). And Hampton 19, it fits on 3 modules. So maybe more options with Hampton 19.

I want every room to enjoy our beautiful view on the north over the acreage and tree line. I know in hot zones, it's better to have the bedrooms on the south, but we suffer a lot more from cold than heat in Bairnsdale! Shading, breeze and Fans do most of the job. But in winter... planning for hydronic heating + Pivot wood heating or similar on the living room wall (shared wall with bedroom 3 in H16, bedroom 4 in H19 as per Pivot's recommendation)

About windows rearranging, exactly as you suggested, I will remove the bedroom 2 W window and make it a N window. Bedroom 1 remove E window and replace with N window here. Ideally I want them to be stacker doors for bedroom 1 and 2. So external shading will be important.

In the house we visited they had massive sliding doors on both N and S in living room. And decent sized deck on S side of the living room. So maybe their S was their North.
Having windows on both N and S of the living room would be great in tropics. And it's definitely impressive. That's 3 walls with windows bottom to top. You just reminded me that it's probably not a good idea. Would you remove the S windows in living room altogether? Or what size would you go for?

Posted Monday 17 Jul 2017 @ 9:18:30 am from IP #
ktb
Member

This is an excellent thread. Thanks so much for sharing all your findings, VinceMD. I think I'm in a similar position, though not as far advanced. Our goal is to build a small weekender on a block of land near Castlemaine.

I've been doing a bit of research myself and wanted to share some humble thoughts and perhaps a few questions...

- For our home, I'll definitely go with all electric. Not just for environmental reasons, but as was mentioned above, you'll be better/cheaper off eventually when you can afford to add solar panels and maybe even some batteries further down the track.

- AFAIK underfloor heating is not just slow but pretty inefficient. I'm wondering if a wood fire heater wouldn't be good enough (see question below).

- I'd definitely invest in LED lights because they are *way* more energy efficient. I'd also avoid downlights to minimise leaks. Just get something on rails, I think they can look really nice: https://lightingcollective.com.au/products/black-track-lighting-kit-2-metre-with-three-lights

- I've also looked at all the pre-fab homes mentioned here. Anchor definitely comes out on top in terms of cost, from what I can tell. I'm a bit worried about quality though. Have you spoken to anyone who's had their home for 5+ years?

One question I have regarding heating:

- I know you're building a larger house than us (we're looking at 2BR). If strategically placed wouldn't a wood fire heater be sufficient for the colder months at least for the living/lounge area? You could, if needed, add one or two cheap split a/c units in the back of the house. I'm not very familiar with fire heater (only used them in holiday homes), but with the right heater, they can spread the heat around the place quite well, no? Wondering if I could stick with just a wood fire heater for a small 2BR weekender...

Keenly following this post.

VinceMD, it'd be amazing if you could keep us posted with your progress and potentially even give us a cost breakdown afterwards. Much appreciated!

Posted Wednesday 19 Jul 2017 @ 10:15:24 pm from IP #
d.darroch
Member

VinceMD said:
So we are going for Hampton 19, which is just longer with 1 more bedroom in between 3 and 2.

Looks good!

VinceMD said:
Note that the Hampton can be built with split skillion roof/facade, which might help with having small eaves all around. I've checked with them. It could be slightly cheaper on split skillion facade.
I like Cube facade more but I'm open. Could even do half/half.

I too like the cubehaus facade. But there are a few problems with having flat roofs. As you said, it may be more expensive, as you need box gutters. Box gutters can also be a bit risky in heavy rain. If they overflow they can flood through the ceiling, & into the house (well designed normal gutters will overflow away from the house). So box gutters always have to be kept clean of leaves, & need to be designed for maximum rain rates.

So the split skillion is probably the more sensible option. I think it's also an attractive option (more so than the average house's hip & valley roof). I'm assuming it would be single skillion over the E & W wings, with split skillion over the living/dining area.

If you go the split skillion I'd have a few questions. Will all rooms have cathedral ceilings, or normal ceilings with internal roof spaces? If it is cathedral ceilings, can you have clerestory (high level) windows, as seen in some of the single skillion designs?

There's a few reasons I ask. If there will be cathedral ceilings, & you choose to have clerestory windows, YOU WANT TO HAVE THOSE CLERESTORY WINDOWS FACING NORTH. As clerestory windows are up near the ceiling, where it is warm, they loose a lot of heat. So they'll need to be double glazed. Also if they face north you'll gain heat throughout the day from sun entering through these windows. SOUTH FACING CLERESTORY WINDOWS WILL NOT RECEIVE WINTER SUNSHINE, SO SHOULD BE AVOIDED IN COOL CLIMATES. If you decide to have cathedral ceilings & north facing clerestory windows the steeper pitched roof will be over the southern portion of the house (bed 1 & the dining/kitchen) & will face south. Unfortunately the north facing portion of the roof will be lower pitched (or flat if you go for a cubehaus on this section), so won't be ideal for solar PV.

If the house will not have clerestory windows I'd pitch my roofs the other way. The flatter pitch facing south (over bed 1 & the dining/kitchen), the steeper pitch facing north (over the living area). This north facing section of the roof would be ideal for solar PV.

Even if you're not planning on installing solar PV straight away (although I think it's probably a good idea), I'd definitely design a roof that will be appropriate for solar PV.

Leaves a bit of a conundrum, north facing roof for solar PV, or north facing clerestory windows. I'd probably choose a north facing roof, as cathedral ceilings may not be a great idea in your climate.

VinceMD said:
If I decide to not have eaves on north side (like the one I saw) in order to get a bigger living room, I'll have to use a long louvered on the north side above the living room stacker doors. Again, need to check it will work with the style... I assume we can't make the living room deeper AND have eaves because the module needs to fit on the truck and on the road.

Yeah, eaves are pretty important. You'll certainly have to sort something if you go for a cubehaus. Looks like a split skillion will give you decent sized eaves.

VinceMD said:
planning for hydronic heating + Pivot wood heating or similar on the living room wall

So your wood heater will have a water jacket, to heat your hydronic? That's a good idea, as you'' have a low mass house & will require more heating when it's cold, when your heat pump will be less efficient.

VinceMD said:
About windows rearranging, exactly as you suggested, I will remove the bedroom 2 W window and make it a N window. Bedroom 1 remove E window and replace with N window here. Ideally I want them to be stacker doors for bedroom 1 and 2. So external shading will be important.

Careful not to overglaze. Evendouble glazed windows are poor insulators when compared to a wall. Overglazing could result in a cold house when it's cold & cloudy outside, & could result in it being too hot when it's quite warm & sunny (as you won't have much thermal mass to absorb that heat in the daytime).

VinceMD said:
You just reminded me that it's probably not a good idea. Would you remove the S windows in living room altogether? Or what size would you go for?

I'm not an expert. I'd guess you'l want some S windows there, for summer cross ventilation & views. Just keep the windows quite small so you don't overglaze. Others here should have a better idea how to calculate appropriate window sizes for your climate/house design.

Posted Thursday 20 Jul 2017 @ 10:12:20 am from IP #
VinceMD
Member

ktb said:
- I know you're building a larger house than us (we're looking at 2BR). If strategically placed wouldn't a wood fire heater be sufficient for the colder months at least for the living/lounge area? You could, if needed, add one or two cheap split a/c units in the back of the house. I'm not very familiar with fire heater (only used them in holiday homes), but with the right heater, they can spread the heat around the place quite well, no? Wondering if I could stick with just a wood fire heater for a small 2BR weekender...

I'm not an expert. I've just read a few things. Wood heater look quite efficient nowadays. With fans, reversible in the winter, leaving the bedroom door open, you might be fine. You could plug in an electric heater (oil to air) and set it to 17 degrees for the night, in case the wood is all burnt up in the wood heater. Just for a weekender, that might be enough and could always upgrade to split system later on.
I looked at http://pivotstove.com.au for efficient heaters. But there are other threads in this forum with more info.

For us, we will be living in the house, going to work, etc. Although some wood heater don't have to be loaded for many hours, it's still not ideal. It takes effort. I go away for days at time and would like my partner to be comfortable and not have to worry about loading wood. Hence the heat pump powering the hydronic system (radiator panels ).
Speaking of radiator, there is also the option of trenches along the sliding doors: https://www.huntheat.com.au/products/trench-heating-and-fan-convectors/
If anyone has got experience/opinion on this, I'm listening. I wonder if that can be setup in this type of prefab house with suspended floor.
I'm also pretty excited about the idea of having towel radiators: dry and warm towels and dry clothes quickly in the laundry!

d.darroch, you give me a lot of things to think about. I'll have to think about the different facades. The 2.7m high ceiling felt really good. It made the whole living room feel so big. I care less about ceiling height in bedrooms though. I like them warm and with a view.

Could PV be installed on flat roof at the right angles, with some sort of accessories? I had thought that we could make it work.
I don't know if we are going to install PV on the first year, definitely soon though.

d.darroch said:
Yeah, eaves are pretty important. You'll certainly have to sort something if you go for a cubehaus. Looks like a split skillion will give you decent sized eaves.

Well, it's always limited by the truck and the permits to transport the house. Looking at Anchor for instance, it does not look like the eaves are that big on the split skillion. You can make the living space smaller to get bigger eaves, but that's a bit of a shame.
Or you can setup something external shading onsite, and therefore not be facing width limitations for transports of the prefab.
I'll talk to the builder soon to know what can be done.
BTW I use this graphic as reference for sizing the eaves: http://anewhouse.com.au/2012/01/shading-northern-windows/

d.darroch said:
So your wood heater will have a water jacket, to heat your hydronic? That's a good idea, as you'' have a low mass house & will require more heating when it's cold, when your heat pump will be less efficient.

From the information I've gathered using a wood heater for to provide hot water to the hydronic system, will make us have to load a lot of wood continuously. It increases the wood consumption a lot. So I haven't been convinced by that setup.
To me the wood heater is a bonus/decoration and extra cold days + ambiance. Whereas heatpump is set and forget.
However, you are right, the heat pump will be running at a time of the day when there is no sun to power it via PV.
We could have massive insulated water tanks, but I don't think it works well.
Heat pump are now efficient and can be used in very cold weather. It will have to take power from the grid I guess..

Posted Thursday 20 Jul 2017 @ 11:51:45 am from IP #

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