That was what first struck me about the system Mr BuildingBoxes has been installing these past nights. Our Zehnder system runs off less than fifty watts. A traditional light bulb runs off 60 watts.
This is the piece of the puzzle we haven’t yet talked about in the Air Tightness, Insulation, Ventilation trifecta that we’re hoping will make our house one lean green efficient…well, house. Simply put, this combination of construction principles (as opposed to design principles) are the kernel of passive house design (says Mr BuildingBoxes). In a passive house, once it’s air tight and insulated, you need to guarantee a minimum number of air changes per hour to distribute air throughout the house and keep it dry. The Zehnder is purpose built to do just that.
The thing that looks more like a Tardis than I expected, takes hot, wet air from kitchens, bathrooms and the laundry and exhausts it outside. Fresh air from outside is supplied to the living areas and on its way there, it picks up the heat that was extracted from those hot, wet environments, but without the moisture.
Moreover, some of our rooms have a lot of solar gain because of our massive heat sink (the concrete midfloor), so they hold a bunch of heat. Other rooms, like the ones downstairs don’t, so we need a way of sharing all that great free heat energy throughout the house.
Zehnder does this with individual ducts, radiating from a central heat exchange unit, supplying each room individually. AND it has one massive sound deadening attenuator box (that’s Mr BuildingBoxes speak for that Tardis I was talking about). It also filters the air as it goes.
The difference between this and what Kiwi’s would associate with a Heat Recovery System is:
· It’s super quiet – no sound travels between the rooms because they have their own ducts and because of that massive Tardis downstairs.
· Really importantly for the long term health of your house, it balances the pressure between supply and extraction. That means hot, wet air from inside the house won’t be forced into your wall cavities creating leaky building syndrome Mark Two.
· And the biggy for us is that it’s fresh air moving around the house. Fresh air that’s been heated by the unit with those clever, super efficient German fans, taking everything we make through solar gain and transferring it into what goes back into the house. Not the same air, just being pushed around room to room.
· For us too, the ducts are smaller and go through the wall cavities – important when you don’t have a ceiling space.
Oh and I’ve changed my mind about it looking like a Tardis, it’s more like a Dalek. Or maybe a cross between the two…
Also, if you were looking for me on stuff.co.nz this week, sorry, they’re having a shuffle around. I’ll be back, but it might not be on Tuesdays, still, the end is in sight so all is well!
It's been a while in the making, but once the ducts were in the walls back some months ago. The Air Tightness membrane went on and the GIB covered the whole thing up nice and neatly, it was time to get those ducts into the mighty Tardis-Dalek...
Seems it always happens, but you hope that it won’t... The insurance report has come through and they will only cover half of what was taken. Less the one thousand dollar excess too. Sigh.
This week on stuff.co.nz I’m talking about building brands in the construction industry, a little sideways I know, but something I find interesting and I’ve had plenty of chats about with various tradies and suppliers onsite and off. And if you were wondering who Chris our plumber was – its Chris from K10 – he’s definitely our no problems only solutions man.
When insurance companies are brand building, ideas of trust, dependability, being companies that kiwis can rely on, are almost always thrown into the pot (just watch a few insurance adverts). But thus far, that hasn’t been my experience. When we were burgled in our home around five years ago it was the same story, yes, you’ve been burgled, sorry about that, but no we won’t pay to replace anything much. At the time, the memories of the Christchurch earthquakes were still fresh in everyone’s mind, so I didn’t feel I had any right to complain. And it’s the same this time, from the comments some of you have sent in about being burgled on building sites, we got off so so lightly. And we’ll be moving in soon to add personal security to site along with the camera that’s up now. When I say we’ll be moving in soon, that doesn’t mean we’re close to finishing (at the moment the kitchen is only half built and plumbing is still weeks away). But the police have warned that as soon as the appliances go in, those burglars will be back. So this time, we will be too. And until then, there’s not really anything left to steal…unless you count mud, bent nails and cigarette butts.
Thanks for all the well wishes after the burglary. And then the other one. We're hoping (really hoping) that insurance will cover at least some of it, but it looks like it's not necessarily going to be straight forward (when is it ever...). The build doesn't care about thefts or the costs of replacing tools and materials. The build just wants to keep on trucking. And so, on it goes. This week on stuff I'm talking paint, choosing your palette in fact. And I think Mike Our Man of Hammers and Mr BuildingBoxes are still laughing at me trying to ask their opinion on the various shades of white.
There was even more of that when I came up with the design for the door to my office. It's a beautiful cedar door, Mr BuildingBoxes said. You're going to paint what on it? Mike Our Man of Hammers said. And then of course, I convinced Mr BuildingBoxes to use his exacting mathematical brain to work out my random (but not) pattern, it was taped up, painted and voila, a new door was born. Okay, it took a little while, but the important part here was that most of the time was in the preparation. Once that was done, it was a relatively simply task to get something old, looking not only new, but pretty funky. I"m hoping its the same with the house, because the preparation is taking forever.
You will have seen the final result of the door on stuff last week and you can see more a break down of how to get there over at Habitat by Resene. I have to say, looking at it all taped up in lime green I almost changed my mind about painting it black and copper, looks kinds Keith Haring-esk. (That's my fifth form art class coming out there. See I was listening) There'll be a few more of these types of posts with Resene if you like to get a bit creative with your paintbrush, so when there is more, I'll add more. Right now though, its down to taping up the house, the WHOLE house, ready to paint...
If you’ve been over to stuff you’ll know that we had a visit from some unwanted guests. The perfect irony of burglars who steal the high tech door locks still makes me almost chuckle. But only almost. Because of course it leaves us out of pocket. How much, we’re not exactly sure and happily, our Contract Works Insurance is hopefully going to kick in. Of course there’s a decent excess ($1000 in case you’re wondering) but given the extent of the stuff they’ve taken, it’s well worth the claim.
Interviewing the police was an eye opener for me about the types of things stolen from building sites, but I guess it stands to reason. It has however, made me nervous about leaving ANYTHING outside. They took our (super heavy) hand made bench for example. The more we look into the things that are missing though, the clearer it is that these were guys with either a shopping list, or a very clear idea of what they wanted. They went through a box of pretty expensive stainless fittings for example and stole a box of square head screws right at the bottom but left the rest.
Then of course was the weird stuff. The hose from our crappy build site vacuum cleaner. If anyone has a guess as to why you’d take that and not the whole machine we’d love to hear it. Mr BuildingBoxes figures they either had the same model and just wanted the hose, or maybe expected us to throw it away now it is utterly useless. I’m guessing it’s something much more random, who knows.
Chatting with a spokesman from IAG (the parent company for NZI, AMI, Lumley and State in New Zealand,) I wondered if they had any advice for would be builders. The short answer, DO get insurance. Contract Works isn’t like Home and Contents because there’s not necessarily a building to break into (obviously). But each policy is different, building materials are usually covered, and some tools, (there’s a catch all phrase about labour and works being covered in an agreed contract) but the policies tend to be quite specific so read the fine print people.
If you’re part of a group home build, insurance will most likely be included in your fee. But if you’re doing a labour only contract like us, or a variation on one, you’ll find part of the contract you sign with your builder (which you now need for works over $30,000 under the Building Act) is an insurance section. Apparently many people overlook this part and come to their insurer once the project has started. But banks usually require a certificate of insurance and most builders will ask for it before they start work.
If you do get burgled on site the advice from the insurers is pretty common sense: contact them asap, call the police, meet with the loss adjustor and go through all the paperwork to itemise and prove what’s gone missing, and have a think about your ongoing site security.
So far, so good for us. We’re meeting with the loss adjuster and our insurance agency NZI, have said it should all be straight forward. In the interim, if you’re building and you get offered these locks in amongst a box full of building goods – call the police – they’ve only been in the country since June so they’re probably ours. And if you get offered a vacuum cleaner hose….well, maybe you can ask the guy why on earth he bothered stealing it.
Over on stuff.co.nz I’m talking about landscaping, something that is completely outside of our scope. We can grow plants, we’ve got a bunch of them germinating at the moment, but knowing that they’re going in the right place and that they’re not going to die instantly…that’s a whole other kettle of kippers.
Happily, we’ve been working with Renee Davis, Head of Landscape Architecture and Design at Unitec and also a general awesome lady. It’s been a really great process for us, mostly because it’s something so new to us and also because Renee has both held our hands through it and pointedly steered us in what feels like the right direction all along the way. I mean look at that plan - comprehensive enough for us to not stuff up!
So a little more on the process? To start with, Renee worked out a site inventory and analysis of soil, drainage, climate conditions, and existing vegetation. Obviously you don’t want to be planting things that are going to curl up their toes and die within months of you planting them, because that costs you cash (and there’s no point planting a tree somewhere your Mr BuildingBoxes really wants a shed). This was a process of discovery for us, we knew we wanted the Lego Engineer and Destruction Specialist to have plenty of room to run around, we wanted to grow a whole lot of vegetables and fruit, we wanted to use as much of the natural features of the plot as possible as about a third of it is covered in bush, and I wanted to be able to dry the washing! This last one goes against the “pretty” of the landscape design, but it’s a practical consideration that has to work for us – because we’re all about keeping our power bill at a bare minimum and with a south facing section, the options are somewhat limited.
We’re building the decks ourselves (just another of the things we’ve added to our potentially foolishly long list). Renee has helped work in how to integrate the vege beds and decks so that I’ll be able to stagger out of bed with a view of my office and the veges, get all inspired, and then potter my way through the broccoli to my desk. In the midst of house sitting through a plethora of different types of houses biggish and tiny, I’m keeping that glorious thought of deck/vege/room of my own on a pedestal. Can’t wait!
Renee does take on some private clients – in her tiny amount of spare time – the woman is super busy! But you can get hold of her through her website.
The GIB going up really feels like a milestone. Like I say over on stuff.co.nz this week, walls just make the house more….houseified. I talked about getting the plasterboard onto site over there (so glad that wasn’t my job) but for those of you interested in more of the detail on this part of the process I thought I’d go into the products a little more here.
Interior magazines are full of glorious bathroom designs with fully tiled showers and walls, but because we just couldn’t squeeze that into the budget, we’ve gone for Athena Acrylic Lifestyle showers coupled with GIB Aqualine®. When we were looking at buying a house rather than building, many were the bathrooms we walked into and realised that steam, moisture and bigger sneaky water damage had destroyed what would have been a nice room. This new build (like most of them) has been a long, expensive process so we don’t want to have to repeat or repair anything for a long (long) time. The GIB Aqualine® has a water resistant core containing special polymers to help prevent steam and moisture penetration so we’re hoping it’s the best insurance against future liability and expensive call-backs.
If you are planning on tiling your bathroom though, it is the top tiling substrate used in bathrooms too. Strengthened with a fibreglass core, it provides a solid stable backing so you can go for gold. Gold tiles that is.
On the ceiling we’re using GIB Ultraline®. The modified core with plaster and fibreglass provides density and rigidity and it’s got a special Pearlcoat coated white surface paper, (doesn’t that sound smooth already – Pearlcoat) making it easier to get a higher finish quality. With all the light coming through our windows that ceiling is going to show everything, so the higher the finish quality the better as far as we’re concerned. Especially as Mr BuildingBoxes is going to be going for gold paiting that ceiling in a couple of week’s time.
And finally, along with the standard GIB plasterboard, we’ve got dual board GIB Braceline® GIB Noiseline®. Its higher density core can reduce noise transmission between rooms and also between floors in two storey homes – important when our two boys turn into heavy footed teenagers. It’s formed part of our bracing structure too – a cost effective way to add to the bracing of the building – win win.
Now it’s down to GIB stopping, and then….painting. Can’t decide if I’m excited about seeing colour start to coat the walls, or terrified about putting my roller and paintbrush to work again!
Yes, really. While over on stuff.co.nz this week I’m talking about the unexpected bonuses of housesitting (and a little on the downside of the constant packing and repacking), we’re still insulating. This time, downstairs with a great new (to New Zealand) product, DriTherm, again from Knauf. It’s part of the Earthwoold glasswool range and is specifically for masonry walls and cavities.
If you’ve been following along a while you’ll know that we have 50mm of ClimaFoam XPS on the outside of the blockwalls, and now with the DriTherm on the inside, we’ve bumped our Rvalue up to R3.3. With the added insulating properties of the block walls we should be toasty warm down there now. And I should add dry, cos while we’ve made sure to seal out the moisture in a bunch of ways, it’s nice to know the DriTherm won’t transmit water into the inner leaf as a double check. While we don’t need to dampen down the sound much on the wall that’s effectively buried in the bank, DriTherm provides great acoustic benefits too so hopefully those gleeful screams of The Lego Engineer and Destruction Specialist celebrating finally having their own lawn, will be damped somewhat.
Like the standard Earthwool glasswool we used upstairs, this stuff is super easy to deal with. All it takes is a measure, cut and place and it’s all done. I have to admit that it did take me longer than upstairs simply because DriTherm is stiffer and so doesn’t provide as much opportunity for measuring by eye – which is of course, my preferred method. The rigidity comes from its silicone treatment and because of that you can see every cut, nook and nick, so I had to get busy with a straight edge and measuring tape which simply takes more time. Once you’ve cut it to the exact size however, it just stands up nice and neatly in your chosen cavity until you cover it up. Job done.
It feels like things are starting to pick up and the place is really starting to look and feel like a house. Yeay! Over on stuff.co.nz this week I'm talking about the air tightness system from ProClima that we've installed - another of the Passive Design principles we've chosen to adopt in the build. As I keep saying we are not trying to achieve PassivHaus standard because we simply cannot afford it. To put it in context: getting the right windows on our build to meet the standard, we would have meant adding more than 20K to our bill (that's over and above the double glazing, LowE glass windows we already have, I'm talking ones that are truly air-tight - but that's a whole other post that I'll come to when I talk more about numbers).
We have, however, been able to put in the air tightness system and we're already feeling the big change in warmth in the building - and we haven't even got the real doors in yet! Seriously, while there is white ice all around outside (which doesn't happen often in Auckland) it's pretty warm inside, and like I said, that's without proper doors and the garage still being open.
In case you're not heading over to stuff, the basic principle of the air tightness system is giving our insulation the best possible chance of keeping us warm. It's a Goretex jacket over a woolly jumper - keeping all the warm in but not letting the cold air outside steal it and make us need to heat the house with means we need to pay for.
The process is relatively straight forward: cut Intello pieces to fit, staple them in place and tape the puppy every which way to Christmas. We also need to tape or fill every nook and cranny we can find, so around power points (where there are special boxes to help with the job), doorframes, floors, ceilings, you name it, we're trying to seal it up. It’s another job we’ve done ourselves with staple guns, a sharp pair of scissors and some seriously specialised tape from ProClima.
We’ve had to think hard about plumbing and wiring – keeping as much of that in the internal walls as possible, because every time we make a hole we have to seal it up. Real good. In the ceiling however, we got round that problem by creating a service cavity, fixing the Intello directly to the frame and then using GIB Rondo battens to create the cavity for wiring and light fittings.
We’re not experts, and a few insulation installers do put it in, but it’s a pretty specialised product so it’s not like the yellow pages are crawling with installers yet so it’s hard to gauge how much we might have saved putting it in ourselves, but to put it in perspective it’s taken Mr BuildingBoxes about four and a half days, plus the blower door test (which is definitely outside of our scope). And speaking of blower door test, if you have popped over from stuff, here are the edited highlights with Jon Davies from ProClima New Zealand.
Happily yes, we did manage to crack the rating we were hoping for, less than 2ACH, which wasn't bad considering, as I said, we've still got work to do. The process of course is to do this test now, while we can access the membrane and seal up any obvious leaks. Then when the linings have gone in and we're almost there, we'll test again to see how we're doing and the rating should drop again. So 2ACH at this point is great, compared to anywhere from 5ACH in a great new build house to 10ACH in a pretty standard one. Should save us plenty on powerbills as we manage to use the heat we've gathered in the insulation and the thermal mass in the concrete slab rather than turning on the heater! And just in time, it's been COLD this winter!
A family of four: writer, scientist, lego engineer and destruction specialist. Our previous home is featured in New Zealand Interior Style and this new project promises to provide plenty of great, green, smart and maybe madcap solutions to new building in New Zealand.