It's been a chilly and blustery week with the 'beast from the east' causing widespread havoc across many parts of the UK.
It has also been the first real test to see how well the house would perform, and with temperatures dropping as low as minus six overnight we have been pleasantly surprised how consistent internal temperatures have remained. We couldn't help feeling slightly vindicated that the effort (and expense) of building to the exacting Passivhaus standard suddenly became completely worthwhile.
It's not been especially toasty inside (generally 20 celsius +/- 1 degree) as the radiators never get that hot, and they never seem to come on upstairs, but it doesn't seem to stop the kiddies from wearing very little most of the time. Solar gain makes a huge difference, with even a couple of hours of afternoon sun pushing the temperature easily up to a comfortable 24 celsius. It's interesting then how much of the heat will be retained through the night as the following morning temperatures are usually a degree or so higher than normal.
The outside walls are noticeably warmer to the touch at head height than at skirting level, highlighting the effect of our our big thermal bridge where the ground slab meets the external wall.
It's supposedly spring now; bring on summer.
...but not quite close enough. Regular visitors will know that we have been aiming for the EnerPHit standard for the renovation works; the final air test was the decider as the previous attempt in June only achieved a combined average of 1.45 air changes per hour (at 50Pa).
We knew the curve was getting steeper to achieve it (exponentially), but we had identified several areas needing work and those had all been 'plugged'. On the day, the best we could achieve was a combined average of 1.18 air changes, so a good improvement but not good enough for the EnerPHit requirement of 1.0 or better. The Air Flow Exponent averaged at around 0.9, indicating that the holes were many and tiny rather than a few large ones.
This was disappointing of course but it doesn't change the way we are able to live in what is still a draught free and extremely comfortable home.
On the plus side we will not now need to have the debate with the certifier about whether or not the loft volume should be included in the calculation! It had been suggested that it should not, which made no sense to us as the loft is within the Passivhaus envelope; a discussion for another day perhaps.
We've learnt a huge amount about airtightness, and the importance of careful workmanship to achieve the high standard required. We think the weak point in our case was the existing cavity wall which, despite our best efforts, was difficult to effectively seal in all areas, particularly where the new build structure attached. We had primarily relied on the parge coat applied directly to the outside of the existing brickwork for the airtight line. Next time we will pay more attention to details internally.
We're at the enjoyable stage of the project when the house is tidied up for photos. We asked James Andrews Photography to take the pics and there are some great shots, now appearing on our new Instagram account. Here's a taster...
We're working towards what we hope will be the final air-test in the next few weeks.
Two leaky areas that emerged during the last forensic test were the gable end walls inside the loft, essentially the inner leaf of fairfaced blockwork, poorly jointed and therefore drawing in air from the cavity behind. Hindsight being that wonderful thing, we should of course have dealt with this before loading the walls up with Paul, ductwork, the boiler and no end of pipework and tanks. Alas, we didn't anticipate the issue.
So after several months trying to find a plasterer to take on this small but fiddly task, and failing, it seemed the only way was to do it ourselves. I mean, how hard can plastering be?
Hard, particularly with the aforementioned obstacles. But it's done now and the plaster is still on the wall; I used Browning, dampening the blocks first to hopefully improve the bond.
The driveway has been paved finally, with a raised platform leading to the front door using the same grey pavers. Thorough job by Liam at Kelly Driveways.
Not before time, I'm finally now insulating the intake and exhaust ducts between Paul and the external terminals. This is to avoid condensation on the ducts, more likely now the temperature has dropped. It's tedious forming the flat 25mm thick Armaflex sheet around the bends, but it'll be a good job done. Unfortunately I'll finish and then have to do it all again to provide 50mm thickness.
Armacell's data sheet says the vapours may cause drowsiness or dizziness; high as a kite more like.
The sun shone for several visitors yesterday at our annual International PassiveHouse Open Days event, flying the flag for Manchester. It was encouraging that many of the visitors were students showing plenty of interest, and knowledge, of the Passivhaus principles.
Need to keep the postman happy - almost looks designed...
The post drops into the garage to avoid breaking the Passivhaus line. Has anyone designed a PH postbox?
We've spoilt ourselves to a new garage door, nothing fancy but it does have a hoofa doofa; always wanted to drive into a garage without getting soaked opening the door. Need to make some space in the garage now.
And that's the last of the cedar cladding to be installed, apart from the gate, the bin store...
Finally, now the temperature has dropped, we have discovered a disadvantage to living in a Passivhaus.
Our children have become used to wearing very little inside, such that when it's time to go out there is great reluctance to wear anything near appropriate for the cooler conditions. Hardy perhaps, but shorts and t-shirts really aren't enough now.
Russel and Anna Hayden