There’s a quote I love: “Writing is a concentrated form of thinking. I don’t know what I think about certain subjects, even today, until I sit down and try to write about them.” (Don DeLillo). Writing ‘470’ was like that. I wanted to think through what it would be like to live in a climate changed world, what it would feel like, what skills, resources, attitudes, preparedness I might thank myself later for having made. It was rigorous thinking, for a couple of years.
There are two scenes in ‘470‘ set in a 2034 heat wave. Researching them, thinking through how it would play out, then writing them, let me know what I thought about the liklihood and risks of heat waves in the near future – that setting up for heat waves in the high forties is a critical bit of preparedness. (46°C is 115°F for those of you in USA). There’s a lot to say on that topic, and as I sit down to write this, I still don’t think there is a better way to write it than those chapters. But here is one little bit of that thinking that we’ve put into practice.
Much of the retrosuburbia writing about energy use and energy conservation that I see is about heating, but heating isn’t the issue here. And that prompts another thought I have regularly about permaculure, about swales and herb spirals and sociocracy – it’s not about the solutions, it’s about design, and design flows from close, open-eyed observation of a site. But where was I? Back to the point.
Here, it is cooling, not heating that is the main challenge, even now let alone in the future. We have an open fire for winter, and if we needed to light it more than a couple of dozen times, I’d need to consider closing the cycle from resource to waste to resource much more tightly. But as it is, we can get waste packing and pallet wood for free, easily, in this urban environment. Hopefully not forever – it’s a criminal waste – but we can also do without a fire if necessary. Ash goes to the chooks, smoke up the chimney, and again, if we lived in a cooler place I’d need to consider whether that smoke was a pollution, but with our sea breezes and low number of neighbourhood wood fires, it’s small stuff that I’m not sweating.
This year, so far, we’ve only had one hot day – 39°C – but that’s a La Niña artefact. In El Niño years, we can easily have several days in the 40s by now, and more to come in summer. As climate change bites, that number will increase, the heat will increase and the duration will increase. And the thing that is not often talked about is that the (privatised) electricity grid is not set up to be resilient to heat waves. Coal fired power stations are the opposite of resilent. The disaster that we will need to mitigate is a heat wave with the power down.
There are many things to consider, and no one strategy will cover all the needs – a survivably cool place to sit it out, pets and livestock, neighbours and vulnerable people, gardens and food, refrigeration, water, news, emergency services, concurrent threats like bushfires – so this is just one little bit of the measures we’re working towards. But it’s a nice one, and I’m excited to have it in place.
It’s a powered roof top ventilator. It sucks hot air out of the roof cavity, initially at low speed when the temperature reaches 30°C increasing to maximum speed at 45°C. Whirlybird extractors are powered by wind. This one is powered by a 24VDC motor that works when it is hot, not windy. It uses a fraction of the power of an air conditioner – most of the work is done just by the physics of hot air rising. This is a good thing for comfort and energy efficiency in regular summer heat, but more importantly it means we should be able to run it on battery or stand alone solar power for an extended period in a heat wave.
At its maximum the fan in the ventilator will suck out nearly 650m3/hr of air, and because hot air rises, it will be the hottest air. We’re installing a floor vent in a cupboad in the very centre of the house, that we can open up on those days. If we close up everywhere else, it will force that 650m3 of hot air to be replaced with with cool air from under the middle of the house. It’s the classic permaculture cool cupboard idea, applied to a whole (small) house.
We’ve put ours on a separate circuit to the house (with a caravan plug) so it can be plugged into our regular grid connected solar power, or, if the power goes out we can plug a back up battery charged from stand-alone solar panels to it.
This is the one we’ve chosen. We have no commercial interest in them, or anything to gain from promotion – this one just met the requirements of the system and had good reviews. Here’s hoping it lives up to them! We’ve only had one really hot day since it went in and the difference was noticeable.
Next post in this series will be about the western wall grape-shaded pagola and outdoor cooking area.
We bought a solar vent, which is standalone. We have had issues with the thermostat which turns it on and off at the set temperature so we had our electrician set it up to turn on in late spring and off in early autumn. We can also do a manual override. Not perfect but when we bought it during the El Niño cycle it made a huge difference to our inside temps.
Hi Linda,
The solar exhaust is a great idea! My concern with the “cool cupboard” idea, is that on a hot day you’ll be replacing cool air under the house with hot air from outside the house, which will lead to more heat entering your house through the floor — unless I’ve misunderstood your plan?
Cheers, Angus
This is true Angus, but the air has got to come from somewhere, and there is a fair volume of air under the house that is much cooler than ambient. It’s the coolest available air. The idea is that air drawn in to replace it will still get a session under the house to get cooled by the big bank of permanently shaded earth there. If I had the means, I’d plumb it into the longest run of underground pipe I could manage.
There are few days that are so cold I can’t manage by adding more clothes, but as you note, heat is something else. As my night time temperatures are always lower, sometimes significantly so, the solution I would like to one day install is a whole house fan. The fan is installed in the roof space and because of its blade size it pulls in large volumes of outside air at a low speed. Depending on the configuration of the house the system can use simple vents or be ducted. They don’t use a lot of power. It requires the house to be closed up during the day to conserve the coolth, but I’m doing that already. Pulling in subsurface air from buried pipe is such a brilliant tool, but it would take a bigger yard than mine.
Linda
Great research. I’ve used your technique in a single space tilt slab factory in Melbourne. In summer at night when the outside temp was lower by 7c than the factory temp a large roof-mounted fan (1800mm diameter) would power up blowing the colder outside air into the factory. The hot air was expelled through a roof vent. We couldn’t run it during the day because of the noise.
It was fantastic at keeping this large work space at a very comfortable temperature during Melbourne’s heatwaves.
BUT…. this factory didn’t have a seperate roof cavity like most houses. So when your roof fan starts up how does it suck up cool subfloor air into the living space in your home?
Hi Robert, we’re putting in a vent in the floor of a laundry closet in the middle of the house, (covered with crimsafe to keep critters from using it). In winter, we cover the vent with a carpet square. In ordinary summer weather that’s enough – there’s enough gaps for hot air to find a way into the ceiling. In real heat wave weather, we can open the cupboard door and raise the manhole cover in the ceiling, and close up all the doors and windows to force it to take that air.
I can see where this would be absolutely necessary for a house with steel roofing, I wonder though how well it would work on a tiled roof. My experience has been that tile roofs are much less ‘tight’ and there is always some air coming in and out through the gaps between the courses of tiles. Concrete tiles anyway. In any case I would think that the ventilation as set it would draw in air through these gaps rather than from lower down in the system if the roof was tiled, although this would no doubt still provide some cooling,. Just a thought, probably worth some investigation. 🙂