24 July 2011

7 Days to an Energy Efficient Home

Day 1: Ignore almost all the Advice you get!

This 7 part crash course in making your home more energy efficient is going to be a little different to the usual advice that is doled out by governments and other well meaning groups.
You know the advice you get from the Government, your Energy Company, and all manner of ‘energy activists’. It all seems to be the same:
  • buy energy efficient globes
  • wear warm clothes in winter
  • switch off all your chargers at the wall
The problem with this ill-thought-out, often patently obvious and, I think, downright patronising advice is that there is absolutely no numbers-based methodology behind it.
Case in point:
This chap has devoted his life to stopping climate change by telling everyone that will listen that all they need to do is unplug their phone chargers:
http://www.unpluggit.co.uk/info.php The truth however is that phone chargers use almost zero energy in standby. If you are interested in the real story there’s a great article here:
http://www.inference.phy.cam.ac.uk/sustainable/charger/ The truth is, that if everyone in the Australia pulled out their phone chargers as soon as their phone was charged, the national power consumption would reduce by 0.01%. What about the other 99.99% ?
Well, over the next 7 days we are going to concentrate on the vital few energy users in your house that are responsible for 80% of your energy use and ignore the rest. This will give you the biggest energy reduction for your effort and money.
You may well find that after you have implemented all the advice that your home can be 100% powered by a 1 to 1.5kW solar system
So we are nearly at the end of Day 1 and we haven’t saved any energy yet, just whined about how ineffective most other ‘save energy’ advice is!
Well that will all change tomorrow, here’s what we’ll be covering:

Day 2: We’ll find out where the biggest savings can be made for a typical Aussie house like yours.

Where is your energy going?

The average Aussie house uses 16 kWh of electricity per day.
What is a kWh? It is a kilowatt hour. That means the amount of electricity used by a 1kW electrical device if it is left on for an hour. An example of a 1kW device is a small pool pump.
Another way to visualise a kWh is:
  • 1200 electric shaves (> 3 years)
  • Drying your hair 15 times
  • 4 TV evenings
  • Listening to 15 CD's
  • Using a (small) refrigerator for 24 hours
  • 20 microwave meals
  • Drill 250 holes
  • 4 evenings of light with 60 W incandescent lamps
  • 20 evenings of light with 11 W compact fluorescent light
If you can dig out a recent electric bill, have a look at it. It will tell you what you averaged per day over the last 3 months.
There are a lot of homes in Australia that get by on 5-6kWh per day. And these aren’t super efficient green homes. They have just followed a methodical process to see what their top energy users are, and then made a small investment to fix up the worst performers.
Yesterday, I droned on about how important it is to focus on the big energy users in your home first - if you want to make the biggest reduction with minimum investment.
Here’s a breakdown of energy use in a typical Australian household:
Typical Australian Residential Energy Use
Source: South Australian Govt
If you look at this chart, you can see that 80% of your energy bill is used by just 4 segments:
  • Heating and Cooling
  • Water Heating
  • Other Appliances
  • Fridges and freezers
So these are the things we are going to concentrate on over the next 6 emails.
By the way: see how lighting only accounts for 7% of your bill and standby 3%? So why does almost all the advice you get from everyone else start and end with “Change your globes and switch everything off at the wall”
Don’t get me wrong, it is quick, cheap and easy to swap out your globes, but…. You will make a tiny difference to your bill compared to addressing the ‘big 4’ above.
Why is it then that these ‘energy efficiency’ companies that are springing up everywhere only ever offer to change your globes and nothing else?
If they were serious about bringing energy use down, lighting would be a low priority, and space and water heating would be top of the list.. Something tells me that they are being hired by the electricity generators as a token gesture, so that they can tell the pollies that they are “doing something”….
Rant over. Sorry, but it really winds me up to see so many people putting so much effort into telling people to do so little!
Tomorrow: Your number 1 Energy Efficiency priority: How to renovate your home so that your heating/cooling bill is a few bucks per year.

Day 3: We’ll discover how to massively tame your biggest energy guzzler: Space heating and cooling.

Heating and Cooling: Your Number 1 Energy Efficiency Priority

Yesterday we looked at this pie chart.
Energy Use In Australian Home
Which makes it obvious that heating/cooling is the first problem we have to tackle in our quest to make our homes more energy efficient.
Now, you can pay an 'energy efficiency expert' to come round your home and advise you on all this, but to be honest with you it really is not rocket science.
So here's my Dummies Guide to making your home thermally efficient throughout the year:
1) In summer you want to stay cooler in your house than the temperature outdoors (Duh!) To achieve this as efficiently as possible you need to do the following:
a) stop heat getting in the house
b) expel any heat that does find its way into your house
c) stop cool air getting out of the house

2) In winter you want the inside to be hotter than the outside (told you it wasn't rocket science). You do this by:
a) letting as much sun in as possible
b) letting as little heat out as possible
That's it.
So how can you do this as economically as possible? Well here's a check list for you: 1) Let's start with keeping the sun out in summer and letting it in when we need the heat, in winter. A lot of people try to do this with internal blinds. Well I've got some bad news if that is you. By the time the sun has come through the window and hit your blind, all the sun has already got into the house.
You need to block the sun before it gets through the glass. So how about an external shutter? Well apart from making your house look like a prison, they block all the light too! So you need to have your lights on in the middle of the day, plus you end up more miserable than a Pommie in midwinter because you get no daylight into your house.
The best solution is to put horizontal eaves over the north facing windows. Two simple DIY designs will keep you shaded in summer and unshaded in winter and always allow light in.
a) Framed eaves with removable shading:
Passive Solar Eave
and my favorite because it is so elegant:
b) horizontal slats angled to let the winter sun in and the summer sun out. This is achievable because the sun is higher in summer and lower in winter.
The pictures below show how effective they can be in both summer and winter (picture source: Sunergy Design)

2) The next thing you need to do is stop the heat from your house leaving through the roof, walls and windows. This is achieved by Insulation, Glazing and Gaps. And you need to fix up all three if you want an efficient home.
a) Insulation: Get your ceiling insulated. In winter, hot air rises and most of it will disappear through your ceiling if it is not insulated. It will cost you about $1500 for a decent firm.
In summer your roof space will act like a big radiator and insulation will minimize how much it heats your house up.
There are very few excuses for owning a house without ceiling insulation.
And while we are talking about your roof. Those whirlybird vents are actually very good for cooling down your roof space in summer. There is a myth that they let lots of hot air out in winter too, and that cools your house down in winter too. That is nonsense. They actually remove a lot of moisture in winter and don't harm your heating efficiency in winter at all. Even better are the mains (or solar powered) roof fans, as they blow about 10 times the volume of air out of your roof and don't require a breeze to operate. They can also be hooked up to a simple thermostat so they only operate on hot days.
b) If you have single glazed windows, you are losing 40% of your heating and cooling through them. They are evil. They have similar insulation properties to a piece of paper.
If you have the cash, get double glazing. It's a great investment. Otherwise there are cheaper alternatives: like these guys.
Again, a single glazed building simply cannot be thermally efficient in any sense of the word.
c) Gaps. The average Aussie home has enough gaps in the building skin make a hole the size of a house brick. The gaps are under doors, around electrical outlets etc.
Imagine knocking a house brick sized hole in your wall. Then imagine how much heat you would lose through it on a winter's day. That should give you the motivation to get a caulking gun and some $10 draught stoppers for the doors!
If you do all the steps above you will find that, if you have air conditioning, you will only have to use it a handful of days per year.
As for heating; here's an interesting graph that compares CO2 intensity of different heating methods, I'll let you make your own mind up:

Heating and CO2 intensity

Sorry that was a bit longer that I had planned! Let's sum up in 5 sentences: 1) Put properly designed awnings on all North facing windows
2) Insulate your ceiling.
3) Install a mains or solar powered roof fan, or a whirlybird.
4) Sort out your windows. Either go for double glazing or a double glazing alternative.
5) Fix up your draughts and gaps.
Do that and you will have fixed 80% of the thermal problems in your home.
Tomorrow we look at your water heating options.

Day 4: We’ll decide if you should upgrade your water heater.

Day 5: We’ll look at all the appliances in your home that run 24/7, and find out how to cheaply and easily measure which ones suck the most electricity.

Day 6: We’ll look at all your ‘single use’ appliances and figure out which ones need your urgent attention.

Day 7: We’ll set an energy use target for your home, and find out how to cheaply monitor your whole home’s electricity use to try and stay under that target.

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