Energy Efficient Home

A few people wanted to know a bit more about my house. It is interesting in a number of ways so I will make a start. This is a very long post/article. Pictures to come.

1980s house

The first thing to say is the my house was designed to be a solar efficient house in the 1980s. It is at an angle on the block so that it faces exactly north along one long side. That side has close to 80% glass on it. The house was designed within the limits of what could be done at the time and the intention was to use as little electricity as possible (the only energy utility then). Heating was with a slow combustion heater and, of course, the sun. Boxed in pelmets and heavy curtains on the windows were designed to handle the cold winters in Canberra and to keep the heat out on Summer days. Lots of opening windows and sliding doors were incorporated to provide air flow on Summer nights when the air is cool and to allow the internal rooms of the house to be isolated. Isolation of the rooms meant that you could heat a single room without much need for energy. The north side rooms would be very warm in Winter and the south side ones quite cool. Windows were single glazed because double glazing was not common then. The frames are cedar and therefore very good at insulating the hot and cold. North side rooms have cathedral style ceilings that keep more air mass warm or cool. The floor is concrete slab with dark slate to absorb heat. Cooking was a traditional upright electric cooker. Hot water was originally solar but it broke down when the house was rented out in the late 1990s and was replaced with a large electric tank heater. Windows were covered with heavy curtains, blocking a lot of light even when open. Insect screens further cut down the light so that even on sunny days there was a need for a light on. The bathroom, laundry and toilet are on the south side so are a bit dark too. The south side could be quite cold in Winter and cool in Summer. The construction of the walls is brick veneer and the bricks are quite dark. This means that the west wall gets very very hot in summer. Despite wall insulation, this wall makes two bedrooms go to 35 degrees or more in January and February. The only way to cool them down is by opening windows or ventilation. The whole house is heavily insulated with fibreglass batts – with the strange exception of one wall of the kitchen that has no insulation installed.

Good but not great

So this is how it was. Good but not great. Curtains were quite effective at keeping the house cool in the summer and warm in winter. The downside was that they blocked the light so that electric lighting was needed even in summer. Also having to get the curtains closed by the time the sun went down in Winter could be a problem if I was not there in time. Similar thing in early and late Summer when it was essential to block the sun with the curtains and close windows early in the day. 1980s down lights were installed along the south and in the connecting hallway. That was all very nice except that they would allow a strong draught of warm air through the ceiling in Winter. Not so efficient. I could put energy efficient globes in them but that was only part of what was needed to be efficient. Lighting in the main room was from two cords … it needed high power globes to light the space properly. The slow combustion heater was good when someone was home to keep it burning optimally. Not so good for when you were away for any length of time. Without any other form of heating, it meant that warming the house quickly would have to be done with electric fan heaters which are very inefficient. Cooling was only possible by opening windows in the Summer. In the main room this meant opening sliding doors and that works well. Unfortunately it means accepting security risks or closing the doors when sleeping. For five years I was able to burn a large pile of wood that came from a tree that needed to be removed because it was overhanging power lines. Now that this has run out the option of buying wood is not a great one because of the high environmental cost involved. On the North side of the house there is a pergola. On it grows wisteria and grapevines. That works well for the depths of Winter and the peak of Summer. In a Canberra May, you would actually like the sun to get in the windows but the wisteria is still there with its leaves until some time in June. It means that the house felt quite cold up to June and would then be quite good until the cold was past. Wisteria is very good at damaging gutters, roof tiles and the pergola. It also grows quite thickly and eventually blocks out a lot of sunlight in Winter when you want it the most. On one hand it is nice to have a natural sunshield. On the other it is not so convenient or efficient in Autumn/Winter. The idea of using flow through ventilation in the Summer is good for coastal areas which get sea breezes in the evening. Not so in Canberra where the hottest summer nights are quite still. That means that there is a lot of heat still in the house in the mornings. For Canberra, the better way to do it is to have a “heat chimney” – this is a high point with an opening in the roof so that hot air goes through that and cool air comes in through windows. The air outside cools rapidly with our altitude (600m above sea level and being inland). The West wall has two narrow windows in it. They were covered with heavy curtains as a heat barrier. This meant that they were only useful for light in spring and autumn when it was ok to have them uncovered. They really need complete covering in Summer and to be open in Winter. An awning can handle blockout of the direct sun in Summer but it still got very hot through the glass. The heavy curtains could not be properly drawn away from the windows so were not that good in Winter either. On top of this the opening windows leaked air in any wind. I had hot rooms in Summer and cold ones in Winter. Getting any ventilation to these rooms was difficult too, being at one end of the house. An electric hot water service with enough capacity for 6 people was not a great thing for me. It wasted a lot of energy and it seemed silly to use one of the few potential storage areas for hot water. Solar hot water is much better these days and even gas instant is far superior. In the kitchen there were quite a few issues. Firstly the appliances (really only a range hood and a stove) were old and not at all efficient. The taps were starting to fail and leak. The sink was big but I prefer to use an efficient dishwasher once or twice a week to do the dishes. If done properly, this is a good thing.

Sensible things that I was able to do

Lets consider some not sensible things first.

  • Putting in central heating and cooling would solve the comfort things.
  • Keeping the electric hot water would have been cheaper – just using a lot of electricity wastefully.
  • Putting in three gas heaters to heat the house.

In recent times there are several things that have become easier to do when making a house more energy efficient:

  • Double glazing is not readily available and not too expensive to retro-fit to timber window frames
  • Gas has been connected in the street to allow gas appliances
  • More efficient appliances and lighting is available
  • There are other options for heating a house with sunshine – something which Canberra has a lot of in the cold months.

Starting with the small things and the more urgent ones, I replaced the hot water with a demand gas system. I did not go with a solar hot water system at the time because the technology was changing and there were some silly rules in the ACT that prevented having a solar heater installed inline with a demand gas heater. The rules have changed and the evacuated tubes that work so well in Canberra are a standard now. At the same time, I had a small Rinnai gas heater installed. This is at the entrance and pushes hot air into the hallway and kitchen area but also warms all the house because of the way it is all in a straight line. That heater warms the house to a comfortable temperature in an hour on all but the coldest morning. Best of all, the heater works on a timer so that it is convenient as well as effective. This heater is called a small room heater. The reason it works well is because the house is so well designed to keep the heat in. I also had a reverse cycle air conditioner installed. it gets used only in the June/July and January/February months to deal with the extremes. It was partly a temporary measure and partly a recognition that I needed to provide cooling when there was a run of hot still days. Then I replaced the incandescent globes with energy efficient ones. Initially, I put mini fluorescents in the existing down lights. Later, I replaced the whole light unit with sealed high efficiency lights. The effect of that in Winter was to significantly raise the temperature overnight and when the heating was on it was needed less. With the old fashioned down lights you could feel a jet of hot air in the ceiling space above the light – very inefficient. I also found some 48 watt mini fluorescents that worked well to light whole rooms instead of using 2 x 150W incandescent globes. At the time I was using the wood heater on weekends and other days when I was home and it meant that my energy bills were quite low. They had dropped by 30% over the first year I was in the house. The next step was to cover the west windows with external louvres to keep the summer sun out. That worked well enough for Summer but blocked the sun in Winter. Using weather seals reduced the air leaks. At the same time, I put a Tastic fan and heater in the bathroom. That fixed the noisy exhaust fan and also provided heat for the cold months. Heat lamps work well for a bathroom when they are only on for a few minutes and warm you directly. Replacing the taps with ceramic valve ones stopped the leaks and an efficient shower rose saved water and particularly hot water – it also stopped the mould because there was no more constant damp. Recently, I have done quite a lot more work. I renovated the kitchen. When I did that, I got a dishwasher that takes hot water from the tap rather than cold. This is so that it uses the hot water provided by solar or gas rather than electrically heated. That saves quite a lot of energy and even cost over time. I also replaced the fairly new refrigerator with a smaller and more efficient one. It is more efficient because it is fuller than the larger one. If they are mostly empty a refrigerator cycles through it cooling more often and uses over 20% more power than if it is close to full. The model I chose has a smaller freezer so it uses about 60% of the electricity of the older one. With gas cooking and a much more efficient range hood, things are much better. A range hood is essential for a house that is well sealed from air leaks. The best thing of all was to double glaze. Near the entrance (where the gas heater is) the glazing has made a very big difference. This place is the warmest in winter when the gas heater is on so stopping heat going out the small windows was a good thing. It made a very noticeable difference. The biggest difference is in the kitchen, which faces south and was always dark. Now the windows are all double glazed and opening windows are sealed up. This means that the kitchen can be the warmest room when cooking in the cold weather. It is also full of light in the daytime. Without curtains it is warmer than with curtains before. Removal of fly screens and window frames for the opening windows has let better than 40% more light in. I also put a light tube in to light up a spot that was always very dark. I probably did not need this, now that I see how much of a difference double glazed windows and no curtains has made. In Sumner, I expect that on the hottest days, there will be a lot less heat in the kitchen – you could really feel the heat coming through on days around 40 degrees despite it being on the cooler south side. Another great thing is a skylight or roof window in the main room. This is the room which would be dark in the mornings when curtains are closed as well as in the Summer when the curtains were closed. Now the skylight makes it light and sunny in Winter and that is pleasant. The biggest difference will be in Summer. It opens and will let hot air out at night while the inbuilt blinds will reflect the light and heat during the day (some heat will get in but that si acceptable for the overall benefits). It means that the house temperature should drop by 5 degrees more in the hottest weather. The skylight can also shut itself if there is a thunderstorm. That is the kind of design I like. In one of the bedrooms (so far), I have double glazing too. However, I am keeping the opening windows so that I get the cooling benefit in Summer. On the west wall, I am putting a sliding awning that is like an external blind to keep the sun out in the warm months. In the cooler ones, I will have it open and let the light in. An internal blind keeps privacy when I want it and lets the sun stream in on a nice day. I can remove the heavy curtains in this room as well, replacing them with blockout blinds. I will do that but not quite yet. I will be putting a roll-out sunshade under the pergola and removing the wisteria. That will provide total blockout of sunlight and total sunlight when I want that. The cost is moderately high but the benefits over time will be worth it. Once again the double glazing makes a very big difference to comfort in the cold. I expect it to make an even bigger difference in Summer. Now some very big things. I decided to install an active heating system with a solar panel on the roof. This system is able to collect warmth from the roof mounted solar panel and even the ceiling cavity. It then distributes the warmth to the parts of the house that were previously cold. Since it was installed the temperature inside has been from 16 to 22 degrees in mid afternoon. Previously, the temperature would be as low as 12 and only rarely up to 20 degrees just with the sun shining in. Not only that, these temperatures would only be reached in the north facing rooms. The south rooms would be 5 degrees cooler. As the days get longer, the house gets warmer earlier and stays warm later. I have cut the gas heater back by 2 hours a day and it is actively heating much less than before. That is partly because of other efficiencies but also because the house is much warmer overall and therefore does not need heating up. Gas bills are down 15% but that only part of the double glazing and heating has been in place for the billing period. The solar heater also provides much better ventilation overall while heating the whole house. Removing the slow combustion heater means that there is much less dust around now too. It makes the house much more convenient and comfortable – even in the middle of Winter here in the coldest main city in Australia. Final thing that is happening is to add the solar hot water. That is delivered but not yet installed. When it is installed it will mean that the gas hot water will be turned off unless there is a long period of cloudy weather. Showers etc will be almost no cost. From a low energy house five years ago, this house is now a lower energy house that uses about 40% of the normal energy for Canberra. At the same time it is more comfortable than most houses. Most of all, I feel good about it.

Where next?

Three more things that I want to do.

  • Install insulation on the outside of the west wall to keep the heat out in Summer and retain a bit more heat in Winter. Insulation on the outside means that the thermal mass in the house is higher and that means more stable temperatures.
  • Install the awnings under the pergola all along the north side and build a solarium/conservatory to allow better outdoor living. I intend to put a chimenea there for the winter to make it a good place to dry clothes. In Summer it can be a place to spend some time outside in the evenings. The awnings will make a big difference in spring and autumn when I will be able to control the heat much better.
  • Finish the double glazing of all the windows in the house.

I probably will not put in any PV electricity generation. I do not think that it is a good economic proposition right now. It may be in the future but it is more hype than good sense at the moment. There we go. Another long post 🙂 Here are some of the people who have helped to do all this. Danny Pocock is an excellent installer for the Vellux Skylights. He does an excellent job and is so easy to work with Peter Magassy of Double Glazing Conversions is also very easy to work with and is very knowledgeable. He has managed to find some special glass types for me so that we can maximise the solar input during Winter and maximise the insulation on the South side windows. He really knows what he is doing and the work is also excellent. Hilton Fletcher of Pure Solar is also another very knowledgeable person and the discussions we had on the siting of solar hot water in Canberra were rewarding. HRV and Solamate are an interesting organisation. The technology is quite elegant and potentially very flexible for similar purposes. My house is part of a pilot to see what should be done to make best use of their systems in Canberra’s quite unusual environment. We are monitoring performance and I think I have some useful suggestions for them. Just today, I got a followup with some information that will help optimise the performance of the system for Canberra. I will not mention the local supplier of gas and the ACT regulator here because I had to argue strongly with them in the past when trying to get solar hot water installed with a demand gas system. As a result or independently, they have changed the rules now.

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