Monday, December 15, 2008

The low down on downlights

"Down, down, down with halogen down lights!" is my new mantra. "Don't do it!" I yell passionately in my energy auditing nightmares.

Quite simpy, halogen downlights are a disaster when it comes to energy efficiency, for the following reasons:
1. they are energy guzzlers
2. they create gaps in your insulation, reducing thermal efficiency dramatically
3. they get hot and so make their own little convection current which sucks the warm air, that rises to the ceiling, up into the roof space... making the pressure difference (or stack effect) in the room greater and drawing more cold air in from the cracks and gaps near your floor. Goodbye heated air, goodbye comfort and ooroo money!

When we run an air leakage assessment, standing beneath a downlight is like standing beneath a small ceiling fan, as air rushes in from the roof space. The thermal image above is of a downlight (not switched on) while we are depressurising the house - the rays of yellow are caused by the warm air from the roof space being drawn in around the edges of the unsealed and uninsulated, hot, energy guzzling downlight! Imagine the opposite happening in winter as you spend your precious pennies trying to keep your house warm... because that is exactly what happens :-(

A couple of other good reasons to avoid downlights:
a. they make gaps in the ceiling through which insulation fibres, dust, dirt and pollutants can drift into the house
b. they are a fire hazard

Read a more thorough analysis by Four Corners' reporter Jonathan Holmes and check out the options for making the best of a bad bunch if you're stuck in a house with lots of standard halogen downlights. There are several places online where you can check out more energy efficient downlight options and downlight covers that reduce the gaps in your insulation and the risk of fire.

Friday, December 5, 2008

Passive solar & sustainable... but how leaky?

Ric Butt, of Strine Environments, designs unique, passive solar sustainable houses that are typically warm, bright and spacious, with full glazing to the north. The thermal design of Strine homes virtually eliminates the need for heating and cooling throughout the year, even in the Canberra region. They are made from heavily insulated, precast concrete panels with a high quality finish. The panels are made to exacting standards (by Strine Products in Queanbeyan, NSW) to ensure that they fit together perfectly on site, and incorporate all necessary conduits for cables and services.

Yesterday, we put one of Strine's homes to the test with our blower door and thermal camera... and the results were impressive.

Our testing of Canberra homes (new and old) has so far shown the average number of air changes per hour (ACH) at 50 Pascals to be around 20. Modern European homes, built using advanced sealing techniques, aim for 1.5 - 3.0 ACH at 50 Pa (ie. they are very air tight, energy efficient and comfortable) and require mechanical ventilation systems to maintain healthy indoor air quality.

The three bedroom Strine 'Milennium' home, completed in 2006, had just 6.2 ACH at 50 Pa. At normal pressures of ~ 1 - 4 Pa the house was having roughly 1 - 1.5 ACH. For healthy indoor air quality 0.5 - 1.0 ACH are recommended. So the house is very air tight by Australian standards and if efforts were made to tighten it even further the homeowners would need to consider installing a heat exchange, mechanical ventilation system (to ensure good air quality when all the windows, doors and solar chimneys were closed).

The temperature of the precast concrete walls was remarkably even. Comparison of the external and internal temperatures of a section of eastern wall at 11.30 am on a sunny, 25 degree day showed a 20 degree difference (40.8 & 20.6 degrees, respectively).

Strine Environments is a unique partnership between Strine Design, Strine Products and Strine Building and can provide a leading edge, seamless environmental design and construction process.

Saturday, November 29, 2008

Energy bills on the rise

Articles just published online, at the Canberra Times and ABC News online, describe how household power bills in the ACT and NSW are set to rise by about $100 year in 2009-2010.

Sealing the air leaks in your home can reduce the amount of energy you use by more than 20%.

Fixing the Floor in the ETS: the role of energy efficiency in reducing Australia’s emissions

This paper isn't about sealing the gaps around your skirting boards. Its about how sealing the gaps around your skirting boards, and implementing other energy efficiency measures in your home, could make a meaningful contribution to greenhouse gas abatement via a modified CPRS.

Dr Richard Denniss, director of the Australia Institute policy think tank, says that the CPRS does not reward energy efficiency, making it futile for home owners or small businesses to invest in tackling climate change.

"No one wants to hear this policy home truth - its like farting in the elevator, " Dr Dennis said.

He argues that Australia needs to develop a secondary market to assign a value for for household and small business energy savings and make them count as part of a national effort to cut greenhouse emissions.

Read the full research paper here.

Monday, November 17, 2008

In the press

Today the Canberra Times ran a story on us which you can read here.

All a bit abstract?

Wondering what the gear looks like? In the background of this shot (courtesy of the Canberra Times) you can see the 'blower door' or... fan depressurisation, air leakage analysis equipment. In the foreground you can see the thermal imaging camera. The large fan draws air out of the house causing the air outside, at higher pressure, to flow in through all the unsealed cracks and gaps in the building envelope. In this photo, you can see the hot air flowing in through the gaps above the glass doors, in the thermal image.

Using accurate pressure gauges and special software we quantify the air infiltration rate of the building in terms of air changes per hour (ACH) at particular pressures. The international standard for comparison is ACH at 50 Pascals. The majority of homes (old and new) we have tested so far have been greater than 20 ACH at 50 Pa. At normal pressures (4 Pa) this equates to 4-6 ACH ie. every 10-15 minutes the entire volume of air in the house is leaking out through unsealed gaps... no wonder our homes are so expensive to heat and cool!
(In Europe and North America they aim for just 1.5 - 3 ACH at 50 Pa - this means their houses are so air tight and energy efficient that they need to use mechanical ventilation to ensure air quality is maintained.)

As the fan depressurises the house we investigate with our camera, locating all the areas of air leakage as well as the gaps in insulation and areas of moisture build up.

Thursday, November 13, 2008

Cavity wall insulation OR cavities in wall insulation?

This sequence of thermal images shows a wall in the master bedroom of a 35 year old brick veneer house that had pump-in, cavity wall insulation installed 18 months earlier. (Look carefully and you'll see that the photos overlap slightly.) It was a cool day, ~13 degrees outside and ~16.5 inside.

The yellow/green sections have insulation and the blue areas are empty wall cavities!

The owners report that the house has been warmer since the insulation was installed BUT imagine how much better it could be if it were done properly!

Please note, we have also seen some very good retrofitted cavity wall insulation.

Wednesday, November 12, 2008

Mind the gaps!

Did you know that just 5-10% gaps in your insulation equates to a 30-50% reduction in effectiveness?

Check out the gaps (above) in the ceiling insulation in a brand new, top quality extension.

This thermal image was taken on a 29 degree day. The orange sections are areas completely missing insulation.

Australian houses are super leaky

The Australian government's Your Home: Design for Lifestyle and the Future, Technical Manual 4th Edition (2008) states:

• Overseas standards and research recognise that the weather proofing or
draught sealing of houses is the most effective method of achieving direct energy savings

• Australian buildings leak 2-4 times as much air as North American or European buildings, suggesting a tremendous opportunity for energy savings in Australia

• Australian households produce ~ 20 per cent of our total annual greenhouse gas emissions, of which heating and air-conditioning account for around 38 per cent

Draughts can account for up to 25% of heat loss from a home