Keep calm and shade everything

We are setting records for hot weather again in Perth this week, so it seems a good time to share this summer's improvements to our shading.

Externally, our home is shaded by vegetation where possible, shade cloth protecting most glass areas, and an ad hoc combination including: foam mats in a window, a shed against a western wall, folded trestle table leaning against another wall and an assortment of things hanging on the clothesline. Internally, we have experimented with many ways to create an insulating layer in our windows, to keep the day's heat out. Most of these I have previously discussed here or here: towels, old painting canvas, mattress, cardboard boxes, cushions, styrofoam cooler boxes... All of these are good, but this year we are onto something I think is easier and potentially more effective: corflute board.

For those unfamiliar, corflute is a 'twin wall polypropylene sheet'. Because it has a ripple between its two surfaces it creates a layer of trapped air - exactly what you want for insulation. However, corflute allows some light through (more than, say, a mattress or cardboard box in the window), meaning the house can be not quite such a cave on hot days - although, as most of our recycled corflute came coloured black on one side, we are not benefitting quite so much from this property.

We now put corflute up inside five windows on hot days, and have installed a 'permanent' summer panel of corflute across half of the over-exposed glass sliding doors to the southwest facing laundry. The loungeroom window panels, being about two-thirds window height, leave a 'clerestory' window space, shaded by the small eaves, which allows a bright naturally-lit room.

Initial Time: There was no set-up time besides sourcing the corflute, which we did within other activities. We did make a kids' art activity out of decorating the panels for the lounge window, as I didn't want to live with the brand names from their previous life, but that was optional and fun.  

Initial Cost: Zero. We picked up our first panel of corflute at REmida, the wonderful centre in West Perth that recycles industrial discards for use by schools, community groups, artists and individuals. The rest came via Tyson's dad, a retired engineer, who had a bunch lying around from disused signage picked up on construction sites. If you have to buy them, corflute panels roughly this size cost about $4-$5 each.

Ongoing time or cost commitment: Every day, a few minutes at each end of the day to put the shades up and take them down. 

Impact: A southwest facing vertical surface in Perth in summer receives approximately 3kWh of energy per square metre per day. Its best to shade on the outside, so the heat doesn't get in at all, but providing an insulating layer inside windows slows the rate that heat energy gets into the room, and reflects quite a lot of it back through the glass. Once the heat is inside your house, you have to either live with it or remove it. The latter requires electricity, and lots of it.

As I write, well after dark, it is hot and still, the end of our fourth consecutive day over 40°C (104°F). We've equalled the record for days-over-forty (set in 1933) and if it hits 40°C again tomorrow we will have a new record. Perth is a funny place - although we are all wilting, there is also a slightly defiant 'bring it on' mentality. We wouldn't mind one more extreme day if it meant we got to Break A Record. 

Here at our house, we are feeling pretty good about how little we have used the aircon in the past four days: so far only for three or four hours total. We've done most of the things I talked about last time we had a record hot week, in addition to all our passive cooling measures. The corflute board has been up each day and is working a treat to keep out much of the 3+kWh we've been receiving. We also replaced our big rear shadecloth at the start of summer (the eight-year-old one finally perished) and the new shade has a higher block-out rating (90%). If it wasn't for the hot nights and lack of overnight breezes to refresh the house we probably wouldn't have needed the aircon at all.

Extractor fans, security screens and other passive cooling tricks

The key to passive cooling is ensuring the cool[er] evening/morning air gets into the house, while the hot day time air is kept out.

We often find that by about an hour after sunset the house is warmer inside than out. Our trick for getting the warm air out and the cool air in is: Extractor Fans. They are designed to remove steam and smells, but they are also brilliant for removing hot air.

 

We generally run them for a couple of hours at night, turn them off while we're all asleep (they are not designed to run for twelve hours at a time) then pop them on again in the morning around dawn if the house is still too warm. We also line up our pedestal fans so that they assist the overnight breeze (generally easterly in summer here).

If you've followed this blog even a little you would know that we also shade, shade, shade the house in summer. [If you're new to the blog, have a look at these posts on shading: 1 2 3 4 5 6 7 8] However, its two years since I last wrote about shading so here we go again with some more ideas we've been trying:

- pillows between glass and blinds in the lounge room window (above - NE window, guarded by Eva's scarecrow)

 - cardboard boxes between glass and blinds in the office window (NE window)

- large cardboard tray from a flat-pack furniture item, and a pile of polystyrene cooler boxes, to add insulation to the laundry door - nearly four square metres of glass that gets afternoon sun in summer (SW facing). It can only partially be shaded from the outside, given that it is a door so is not suitable for shading that can't easily be pushed aside.

- a mattress across the window in the children's bedroom (SE window).

- a cot mattress and more flat-pack boxes between glass and blinds in the bathroom (SE window)

- a former painting canvas between glass and blinds in the other bathroom (NE window). Neither bathroom has eaves, so shading these windows in other ways is particularly crucial.

All these shades are removed at night to let the night air in and the day's warmth out. This is possible because most of our windows have security screens. If we were not renters we would fit security screens to the two main living room areas immediately, as not being able to leave them wide open all night significantly hampers our overnight cooling.

After two weeks of lovely cool holiday in Victoria, we last week landed back into the peak of Perth summer. Its hot here! The temperature dipped below 20°C this morning, briefly, for the first time in six days, and maximums have been between 33°C and 40°C for a week, with a similar week forecast ahead. So far we have run our airconditioner for about five hours, on one night when it was not forecast to cool down and the air outside as full of bushfire smoke. Twice in the past ten days guests have commented on how cool our house feels, even noting that one room felt like the airconditioner was on (this at a time it was around 31°C outside).

Initial Time: All the additional shades above are daily measures that we only put up on the hottest days, and require about five minutes at each end of the day to put up and pull down. Extractor fans take seconds to flick on and off; pedestal fans take a minute or two to get into place where they are most effective for night times.

Initial Cost: Zero.

Ongoing time or cost commitment: As above.

Impact: An extractor fan uses around 25 Watts to run. We run three, for about five hours in total: 375Wh per night (about one third of a 'unit' in our system). 

Pedestal fans use around 40-50 Watts. We run four, all night, a total of around 1440-1800Wh. However, we also run them with the airconditioner if its on, so that we can direct the cool air up the passage and into the bedroom, due to the awkward placement of the airconditioner unit in our living/kitchen area.

Our airconditioner uses (roughly) between 1.5 and 2kWh (units of energy) per hour, depending on what temperature we set it to, what the temperature is outside, what the temperature is inside, etc. The night this week when we didn't open up the house, we ran the airconditioner for five hours (and pedestal fans for about twelve hours) to bring the inside temperature down to a bearable level ready for the next hot day - that is, to achieve the same effect that running fans and opening the house usually manages. Overnight cooling by airconditioner (and fans), then, uses about 9-12kWh per day, while overnight cooling by using the evening breeze assisted by fans uses around 1.8-2.2kWh.

Grapes in a rental garden

Grapevines are wonderful. They provide good shade in summer, drop their leaves to allow sun in winter, don't need much water or loving care, and best of all: they grow grapes!

But in a rental garden, are they possible?

We started with a cutting in a pot. As it turns out we have been in the same rental house nearly seven years, but while our lovely vine was getting established in his pot, we could have relocated with him if we needed to. In the photo below he's been settling in for about six months.

By Mr Vine's second summer he needed something to grow up, and we helped him with bits of makeshift trellis in the raised garden bed - mostly recycled items heading for bulk waste, like a rusted clothes drying rack. 

 

But what I really wanted was for the vine to provide shade for the front of the house.

Our lounge heats up not just from direct summer sun, but from reflected heat off sunny bricks. So the challenge was to build a trellis so the grapevine could grow over the garden entrance as far as the roof, without putting up any permanent fixtures.

The main support was a branch salvaged when trimming the gum tree. The trellis comprises two lengths of thick wire, each with loops twisted into them, one lying along the gutter and one connecting the gutter to the gum tree support. Loops between the two wires are connected with pieces of clothesline.

Our vine has now spent two summers growing up the trellis and I am thrilled with this addition to our garden, and to our passive cooling measures for the living area. Grapevines need firm pruning but its not an excessive task. Thus far, only pruning a couple of times a year, the vine has been easy to keep away from the tiles and causes no problems along the roof line.

We know the vine has been through the bottom of the pot for years now. If we need to we can dig it out to remove it when we leave (but why would any landlord want it gone?). Hopefully it can be left to bless future residents.

The grapes are delicious, although they come ripe each year exactly when we are away on our summer holiday. Eva spent the weeks before we left this year telling all our friends to come and eat our grapes while we were away and we were delighted that one good friend did just that, so the harvest was not wasted.

Initial Time: well now... Putting a grape cutting in a pot took about five minutes. Building the trellis took me about five minutes (erecting the gum tree support post) and Tyson about an hour (twisting wires). Growing a grapevine has taken five years so far. We got edible grapes from the fourth summer.

Initial Cost: Zero. We were given our cutting by friends.

Ongoing time or cost commitment: Zero cost. We water with recycled bath, shower or washing machine water through summer, top up the soil with home-grown compost and mulch with leaves off other plants around the garden. Pruning takes about half an hour two or three times a year. As its in a well-mulched pot, there are hardly any weeds.

Impact: Our bricks are shaded a little more of the day and reflect less heat in our lounge window and front door. I don't know if the temperature is actually much cooler but I feel cooler to have a green space rather than the glare of a brick driveway when I look out the window. As it takes so long to be cold enough for leaves to fall here, I have actually cut most of the leaves off to let autumn sun through. And we get to eat home-grown grapes! Which is cool, and also saves a bit on  food miles/ pesticides/ packaging/ etc.

This picture was taken last July - not much sign of leaves dropping off despite it being the middle of winter! Last year we had only one week between the last leaf falling and the first spring shoots emerging. Ah Perth. Not really a climate of four seasons. 

What to do when the hottest week on record is forecast for your city

When the forecast showed Christmas day as the first in a run of seven days close to 40°C, Perth's hottest week on record, we knew it would test our commitment to sustainable living to its edges. The temptation was to pour water on the garden, crank the airconditioner and stay inside (possibly in front of some energy-consuming electronic entertainment). Here are a few things we did to ride out the week of heat without maximising our environmental footprint.

- Wore wet flannels to feel cooler. When I lived in an uninsulated unairconditioned fibro house I used to freeze wet tea towels in a U-shape and wear them around my neck. Now if I am reaching that point I consider we are past the 'bearable' test and its time to turn on the aircon.

- Sent Eva to bed with a squashy ice pack.

- Breastfed baby twice as often... as if the heat wasn't making me tired enough already!

- Kept the fridge as full as possible, filling empty spaces with blocks of ice or cold water, to improve thermal mass by reducing the amount of air to be kept cool. Air is hard to keep cool because it escapes whenever the fridge or freezer door is opened. 

- Shaded everything! In addition to the summer-long emplacements we added some temporary foam rubber mats along the kitchen & rear toilet windows and a tarpaulin over the clothesline. The foam rubber mats make a huge difference. The glass inside was noticeably cooler behind the mats, even before the sun was on the window, and even the cranky thermometer registered about 4 degrees difference between the covered and uncovered glass.

- Washed every day to ensure there was enough grey water for the garden. We always run the washing machine with a full load, so I worked my way through 'sometimes' items (towels, sheets, bathmats etc) to ensure the garden got water every day without having to give it pure drinking water from the tap. On a couple of the hottest days I did two loads and gave the lawn a good soak.

- Played outside in the mornings for as long as possible (for exercise, fresh air and to prevent against cabin fever). Did quiet indoor activities through the worst of the heat (lego, trains, playdough, craft, hide & seek, tea-sets, dolls & teddies, etc). Read a lot of books.

- Had cold or nearly cold showers, cool baths, and used the paddle pool sparingly (and put the water onto the garden when shower/ bath/ play was over).

- Were disciplined about the water-catching bowl in the kitchen sink, and got it out onto the courtyard pots any time it was full to help the plants through the worst of the heat.

- Ran fans rather than the airconditioner for as long as this was bearable. We turned on the aircon on four of the seven hot days - on three of those days for only about three hours. On day three, when we used it first, we set it at 28°C. On day five, when it came on again, the walls of our house had soaked up more heat and we dropped the aircon to 26°C. This is easily enough to cool our living spaces. (Due to the location of the air conditioner unit, even running it like a fridge would not really cool our bedrooms).

- At night, opened the house up to cool as much as possible before morning. We ran the extractor fans to help remove the day's heat and placed pedestal fans in the eastern windows (the overnight direction of cool air if any is coming) to help draw in the breeze.

- Didn't cook (or barely cooked). Christmas leftovers helped with this. We also reheated some frozen meals in the microwave. When we used the toastie maker we then put it outside to cool, so that its heat was not added to the inside temperature. We definitely did not turn on the oven, and only used the stove for about an hour in total all week.

- Went out to places that were cooler (eg the beach, the shady playground beside the lake) or where airconditioning would already be running for other people (Tyson's work, grandparents' house, public facilities). This is not about letting others carry our footprint, but about maximising the number of people each aircon serves, thereby minimising the total number of airconditioners running. On New Year's Eve it was our turn to run the airconditioner on behalf of a group of families. We ran it for 13 hours, but for much of that time had members of up to seven other households sharing it with us.

- Did not increase screen time. We don't have a TV at all. Tyson & I watch a little I-view but Eva is allowed only a very occasional episode of Playschool under extreme circumstances (like the week she was stuck home with hand foot & mouth disease recently). Although I had Playschool in mind as an 'if all else fails' emergency activity for the heat we didn't need to go there - perhaps because the room with the computer is not the coolest room in the house.

Despite being over 42°C on New Year's Eve, with the road still hot under our bare feet at midnight as we watched fireworks in 30°C heat with no breeze, not all the predicted maximums were reached. The average maximum temperature of 39.4°C made it only the hottest week in 34 years, the third hottest week in 116 years of records, and the hottest December week on record, NOT the hottest week ever. Lucky us, eh?! Even though it was only below 25°C for a handful of hours all week, in some early mornings, and didn't get below 20°C at all...

None of these actions had any initial cost, and time commitments were very small (a matter of a few minutes here and there).  

The impact is difficult to measure in any precise manner. Certainly if we had not used passive cooling measures we would have run the airconditioner a lot more in the past week. Its hard to say exactly how much energy this would have meant, as it depends on things like the temperature outside, the temperature the aircon is set to, and how much we would actually have turned it on, but the aircon uses (roughly) between 1.5 and 2kWh (units of energy) per hour. Perhaps as much as 100kWh was saved by limiting our aircon use. If we had run it 24-7 for the week it could have used between 252 and 336 kWh in total.

More importantly, we did not significantly increase our demand for power through a peak period of demand. Demand in peak periods wastes energy all year, as the whole system needs to be built for extremes rather than averages. Minimising peak usage has more impact than minimising average usage. 

I'm quite pleased with how well we did. One more day and I think I would have collapsed. But then, if one more day had been forecast I would have paced myself for eight days as I paced myself for seven this time. Tyson thinks any of our more usual three or four day heat waves for the rest of summer will seem so easy to manage by comparison that we may not turn the aircon on again all season. I have my doubts. I've booked a holiday to southern Victoria in a few weeks to visit my parents rather than ride out the whole summer here - thereby, in two cross-country flights, practically wiping out any footprint gains we make by reducing our domestic power usage here. Ah well. Its about small steps.

Recommiting ready for summer

This is the time of year when a number of our water and energy saving measures need to be reinstated for summer. Doing so involves a recommitment to these actions and, for some, a small degree of maintenance.

So our 'action' for November was not a new action but a recommitment to many previous actions, and in some ways it was the hardest 'action' I have committed to in the three and a half years we have been doing this. Here we go again. Does it never end?? I think life at home with two small children may be shaping that reaction! It is more difficult also, in my experience, to do something again, when it is no longer new and interesting. This is particularly so when it is restarting something that I have failed to continue on with as I originally intended.

After a week of that summer heat smell in the air it was time for Tyson to unroll shadecloths around the house. 

So far we have no new ones this year, but are reinstating all of those from previous years.

One of those along the driveway remains furled as it broke its moorings in winter storms and needs a more permanent hook attached to the bricks to keep it secure. The shock cord for another had also worn through and the rear courtyard shade is definitely not still using the original ocky straps from six summers ago! Overall, though, the shades and their fastenings are holding up well.

The grey water wheelie bin has been brought back into service. I discovered that I cannot get it over the laundry threshold (or if I do I spill quite a lot in the effort) so Tyson sourced some grey water hose to create an extension out the door ($20 for ten metres).

The door obviously doesn't lock like this, but a chock to stop it sliding open any further makes us reasonably confident to leave the washing machine running with its outlet pipe through the back door when we go out.

The original tap connection on the bin had also given us grief last summer, periodically leaking or unwinding itself and falling off, so Tyson purchased a new tank outlet connector (about $8). 

This required sanding the hole for the pipe slightly larger to make it fit, but so far has been a very successful adaptation. The hose we attach to the tap got little holes drilled along it some time last summer to create a drip system for better coverage.

We also put the tubs back into our shower and have grey water on hand again for toilet flushing. This stopped not on account of winter bringing rain, but because somewhere midyear, in late pregnancy, a string of minor ailments over three months had me desperate to change anything that might be contributing and grey water standing uncovered in our bathroom seemed a potential source of winter sniffles. And then we had a baby and I couldn't be bothered with even the small additional effort of gathering and flushing grey water.

The basin in our kitchen sink comes and goes. We are making another attempt at it this summer. Periodically we get fed up with it not getting emptied outside, or getting too dirty, and it is abandoned. Hence it was definitely one of the actions for me that was a recommit, not a routine, as we approach summer.

Costs and times for these actions are detailed in the links above to where I wrote about them originally. Aside from fifteen minutes here or there for maintenance, recommitting doesn't add more time than the original commitment. 

It is much easier, though, to continue with actions that are simply ongoing than to pick up these summer-oriented actions at the end of spring each year. Part of me is tired and thinks oh lets just water with a hose/ flush the toilet/ blast the aircon like everyone else. It was 37 degrees here yesterday (Celsius - that's 100 degrees Fahrenheit, for you in other lands - what some here refer to as 'the old hundred') and the heat made me grumpy. I am home full time with a three year old and a four month old. I get grumpy plenty quick enough all on my own - I don't need any extra grumpifiers! But then... the house kept quite cool most of the day, and when we eventually turned the aircon on (we are not ascetics, after all) I was still grumpy about the heat, so I might as well be sustainable and grumpy. When I look at my reaction, it is being trapped inside that bothers me, and aircon or passive cooling both have that same result. Its grey and raining today... some respite for me to think creatively about ways to get outside as much as possible through summer so I don't get that terrible trapped feeling. Any ideas?

What are you needing to recommit to at present?

Just when you think you can't shade anymore...

When I wrote in December about our summer shading system I thought we had shaded everything we could reasonably manage. But as it got hotter we found more exposed areas that could be protected and added:

additional dense (90% block-out) shade cloth to patch a gap in the rear (southwest) courtyard shading,

 

on very hot days, a towel inside the (northeast) bathroom window, which has no eaves,

on very hot days, an old painting canvas inside the (southwest) laundry glass sliding doors, which get blasted with afternoon sun,

 an old woollen wall hanging on the southwest wall outside Eva's bedroom, and

three towels left on the clothesline all summer along the northwest living area wall.

These also make a good cubby.

Initial Time: Shade cloth: fifteen minutes to bend hooks and hang the cloth; wall hanging:five minutes to put a hook in; towels: 30 seconds each to hang; paint canvas: 30 seconds to balance in place on the grey water bin.

Initial Cost:$20 for shade cloth, zero for towels, paint canvas or wall hanging (which was being thrown out by a family member)

Ongoing time or cost commitment: One or two minutes every week or two to readjust the rear shadecloth as it slips a bit in windy weather; 30 seconds each on hot days to put up the inside towel and paint canvas; probably about ten minutes at the end of summer to pack away for cooler weather.

Impact:A southwest facing vertical surface in Perth in summer receives approximately 3kWh of energy per square metre per day. If the surface is unshaded transparent glass, almost all this energy gets inside the house as heat. The additional shading to our rear courtyard gives 90% shading to about 3 square metres of glass, reducing the amount of heat entering our living area in summer by approximately 8.1 kWh per day. We have a 300% efficient reverse cycle air conditioner in the living area which would use 2.7 kWh of energy to remove 8.1 kWh of heat.So, by shading instead of turning on the airconditioner most days, we are saving 2.7 units of electricity per hot day just with this one area of shade cloth. Put another way, we start to get ahead of the $20 spent on shade cloth on the 27th day of not turning on the aircon. (Thanks Tyson for knowing the numbers!)

In less precise terms, I estimate that this summer it has generally been the third day in any heat wave before we turn on the airconditioner, and last summer I think it was more often the second day. I consider a heat wave to be when the temperature stays at the mid thirties or higher for more than one day. Our airconditioner rarely runs on days with temperatures up to the low thirties (celsius!).

Calculations for the towels and wool hanging shading wall areas, and the paint canvas inside vertical blinds, are more difficult, but we notice that these rooms heat up slower. (In terms of impact, one woolen wall hanging also has a new purpose in life and has been saved from landfill, at least for a while.

Our recent power bill for 22 Dec to 24 Feb shows an average electricity usage of 8 units a day (530 units total), a very very small reduction on the same period last year (10 units less over two months). Most of the past year our average usage has been around 6 units a day, so summer is still presenting the biggest challenges for reducing electricity use at our house. It was the fourth hottest summer in Perth ever recorded (since 1897) and I was going to excuse our tiny reduction by pointing to this fact - until I discovered two of the other three hottest summers were 2009-2010 and 2010-2011. (Its hard to deny climate change when three of the four hottest summers here in the last 115 years were the last three consecutive years... the other was 1997-98). So my alternate excuse for our electricity usage not reducing compared with last summer is that this year I am pregnant and feel hot quicker!

To put our usage in some perspective, however, Synergy (our local electricity supplier) estimates the average household electricity use in WA's southwest grid is 6250 kWh per year (over 17 units per day). Our household's 2011 usage was 2452 kWh (6.7 units per day). We are living a perfectly comfortable existence on that amount of energy.

Shading the house for summer

The arrival of summer means time to roll out the window shades all around the house. Three stay up all year, one is stored away, and another is rolled up and tied on the roof through cooler weather.

east corner

west corner

We installed three new shades this year, as necessary pruning in the front yard had left some of our northeast windows too exposed to morning sun. The most significant of these is a shadecloth wrapping the exposed east corner of the house. We can't quite believe how much cooler the whole house is for reducing the morning sun on this east corner.

We also put a large plant outside the piece of southwest wall that is the head of Eva's bed, to cut the baking sun and try and keep her bedroom a little cooler. The plant doesn't like all that sun so we may need to reconsider how we shade that spot through summer.

Initial Time: Installing the threenew shades took about two hours. Rolling out or reinstalling last year's shades took about twenty minutes.

Initial Cost: Tyson spent about $20 on more shadecloth, timber and shade cloth clips.

Ongoing time or cost commitment: Nothing to do until we roll them up again in late April, except for the two smaller ones that blow in the wind and sometimes need to be pulled back off the roof.

Impact: So far no hot days have required the airconditioner, except for one when we were all sick and normal cooling was not enough. The office, now in the east corner of the house following a room shuffle, hasn't even needed a fan yet.

Past blog entries about shading can be found in December 2010 and December 2009. Note that the tarpaulin shown in the 2010 entry tore in half in strong wind as air couldn't escape through it, so we now only use permeable shade cloth to maintain air movement. We've had a couple of questions about how we fasten the shade cloths, so below are a series of photos to illustrate the detail of the operation.

 

timber on the first shade we put up is starting to weather after four years