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Reports recently published in newspapers indicate that the government’s mandatory energy star rating schemes of homes is rather inaccurate. The scheme has been heavily-criticised by the building industry (HIA and MBA) and they are calling on scientists and the Department of Climate Change and Energy Efficiency to review the way the star rating is calculated for new houses.

Applying the same software to the whole continent is not the right approach either. Most importantly there is another fundamental issue that relates to the way a home is used –which has more to do with the occupants than the actual construction of the house itself.

The main problem cited by the building industry involves the three government-approved tools used to award the star six star rating. Basically it means that there are unacceptable differences between the star ratings produced by the various software tools when assessing the same house. The flaws in the star rating system were discovered after industry representatives, private companies and scientists commissioned independent studies to test the software tools on identical houses. For example the independent testing showed that the same Brisbane house had a variation of 3.2 stars when different software tools were used to audit it. In addition the software tools are easy to manipulate to get the desired results. A side issue is the under-qualified assessors who don’t operate under any quality programs.

The second issue relates to the fact the same software tools are used Australia-wide. Since the software tools mainly deal with heating and cooling to deliver a star rating they don’t take into consideration the varying climates found in Australia. In each part of Australia there will be different contributions of heating and cooling and we have little real data to help us in our understanding of by how much, or whether at all, star ratings will help reduce consumption. A respected scientist explained that the star rating doesn’t actually measure the electricity demand in a given house. So basically there is no correlation between the stars and GHG emissions.

It has been suggested that end-use metering study should be commissioned to determine overall home energy use, energy use by home appliances and the assessment of the thermal performance of the building shell for different housing types. Also, the overall performance of the recently-built six star homes should be assessed to create a valid database to establish if the star rating scheme has in fact helped reduce energy consumption.

The third observation was expressed by a university professor who explained that in reality the behaviour of the occupants of a house dictate the energy consumption. It doesn’t matter how many stars a home has if the occupants don’t use it responsibly. It could be stacked with electrical appliances like LCD screens, fridges or with inefficient halogen lighting. The software tools merely calculate the potential savings based on the fabric of the house, insulation, wall materials and of course the likely heating and cooling. Therefore, it is really up to the individual to act responsibly and to have an interest in reducing greenhouse emissions and of course their electricity bills.

For more detailed information and pdf file go to this site: https://carbonetix.com.au/why_your_5_star_energy_efficient_home_isnt.php

(Ref: http://www.theaustralian.com.au/news/features/eco-threat-to-house-prices/story-e6frg6z6-1225904124270 and
http://www.theaustralian.com.au/news/investigations/energy-star-ratings-in-disarray/story-fn6tcs23-1225899270215 )

I’ve decided to write this blog in a somewhat different format than usual. I thought I should share some of my observations in tracking energy use since I’ve been involved for a little while now in installing, analysing, presenting and monitoring ‘real time tracking systems’ (or ‘carbonrealtime’) as we refer to it.

I was actually really shocked to learn recently -when an environment officer at one of the councils posed the question to a small business audience, whether they knew how much power they used, how much their tariff rates were or how much their actual bills were- that most didn’t have a clue. Out of about 35 people only one knew. The rest had no idea! Even more surprising was the fact that a few of these audience members were accountants and financial advisors. They just automatically pay their bills both at home and for their businesses. How are you supposed to reduce your electricity use, cost and of course greenhouse emissions if you don’t even know (or care) how much you use and pay?

So there are a number of ways to overcome this problem of knowing your electricity use. Starting with the analysis of basic yearly use of the bi or three monthly bills you can get a bit of an idea what’s happening throughout the year. However, many of the larger sites already have interval electricity meters. These record power consumption every 15 minutes and eventually send some aggregated data to the suppliers. This information can be requested free of charge from the electricity retailer and we usually do this on our client’s behalf. Having access to at least a year’s worth of data is extremely useful. If you know how to compile the data and what to look out for one can get a really good idea of a site’s usage profile and how to save energy.

If your site doesn’t have interval metering another option is to install temporary electricity loggers on various distribution boards. Again the data obtained from this is very useful and we often do this for specific circuits at some of the sites. However, the latest revolution is in online tracking. We have developed an affordable real time tracking system that is extremely easy to install and then it’s plug and play. Once set up the device sends the data through the internet and can be accessed from anywhere. The user-friendly interface on the monitor presents all the data in an easy to understand language with graphs and images that don’t need a physics degree to understand. Some of our systems have everything incorporated such as water, gas, electricity consumption/generation and temperature. All these are highly valuable tools for any facilities or environment managers and even for educational purposes.

The ‘carbonrealtime’ systems are used in households and offices greatly reducing energy consumption but schools and council buildings have also installed them to keep an eye on their energy use. From some of these systems a few sites have already identified huge wastage that occur out of operating hours during the night or weekends. The findings from larger council site had effected changes in the HVAC BMS in relation to public holidays, starting and finishing times or discovering faulty equipment or in one instance double charging of electricity over 12 years! Lowering the base load is another useful outcome of using such a system. The tracking system can also be employed to overcome electricity apportioning disputes between tenants, which we often have to investigate for our clients.

With electricity prices going up constantly and with the emphasis on reducing greenhouse emissions; monitoring your electricity consumption is no doubt one of the most important steps towards averting huge electricity bills and the threats of climate change.

Lawrence Berkerley National lab reported November last year on some fantastic research into how “cool roofs” can help slow global warming. White surfaces reflect rather than absorb radiation, and can be effective in re-radiating heat back into space. I’ve only just come across this research today, and the potential greenhouse gas savings are enormous.

Painting a roof white

Painting a roof white

Most roofs are dark in colour, the research by Akbari, Menon and Rosenfield calculated the CO2 offset achieved by increasing the solar reflectance of urban surfaces. For a 100 m2 roof making a dark roof white (with a long term solar reflectance of 0.60 or more) will offset around 10 tonnes of CO2 per year.

A 10 tonne saving per 100 m2 is a large saving. In hot climates white roofs also reduce air conditioning loads. So called “cool coloured” surfaces apparently have only half the benefit.

In California its been law since 2005 that flat roofs be painted white. We should have the same laws in Australia, and should also be legislating that sloped roofs should be white, or at least “cool coloured” as has been the case in California since July.

Assuming it costs $1,700 to clean and paint a 100m2 tiled roof white, and thus save 10 tonnes of carbon, this one measure will provide more climate benefit implementing all of the following:

  • Replacing you gas hot water system with a solar hot water heater (gas boosted)
  • Installing a 2 kW solar PV system on your roof
  • And implementing energy conservation measures that save 16 kWh per day

* Assuming an emissions factor of 1 kg CO2/kWh.

If you don’t have an air conditioner “geo engineering” by painting your roof white won’t save you any money. But in terms of tonnes of greenhouse gas saved per dollar invested painting your roof white – whether at home or at work – could be one of the least expensive ways of cutting greenhouse gas emissions. And it may help you avoid the need to get an air conditioner.

If you have a low carbon footprint to start with, based on this research, painting your roof white could actually neutralise your other emissions. And someone with a white roof is doing more to slow global warming than someone with a 5 kW PV system on their dark roof.

If you’ve bought a new home in Victoria in the last few years the builder would have impressed you by saying its an “energy efficient” 5 star home (or maybe even 6 stars).

Unfortunately even if all existing homes were converted to 5 star homes this won’t get us to the low carbon future we need. And in fact many new 5 star homes use more energy than forty year old 2 star homes. The 5 star standard is misleading, and needs to change if we are to have truly low energy homes.

The major flaw with the 5 star standard is that its focus is solely on the theoretical heating and cooling performance of the home. A 5 star home should use less energy to heat or cool per square meter than a homes with a lower rating. However the largest contributor to greenhouse gas emissions in most Victorian homes now is not heating and cooling – its appliances! Additionally most new homes feature halogen downlights – one of the most inefficient forms of lighting on the market. Finally, there is no validation that the specified insulation and sealing of the building – key to minimising heat loss and gain – is done properly.

Homes now have more appliances in them than ever before. And I’m not talking electric can openers. In particular large screen plasma and LCD TV’s use several times more power than the modestly sized CRT screens they replaced. A large plasma TV will draw 400 watts. To put that in context, if the TV runs 12 hours a day, it will produce more than half the greenhouse gas a car produces in a year. But the Victorian home energy standard doesn’t take appliances into consideration.

Walk into any display home, and it will be filled with bright halogen downlights. For some reason these are still often linked with low power consumption because they are “low voltage”.  To the contrary, to produce a given amount of light halogen downlights use five times as much power as an energy efficient fluorescent light. I’ve heard of new homes that have over 50 halogen downlights in them. If all these lights were on you would require a $40,000 solar PV system to keep them illuminated . But the Victorian home energy standard doesn’t take lighting into consideration.

The Victorian home energy standard does take heating and cooling into consideration. But only on a theoretical basis. Two fundamentals of high performance passive solar design are high levels of insulation and good sealing. The home energy rating specifies the level of insulation and sealing that a building must install in a given home. But unfortunately there is no inspection in place to verify that this level of insulation and sealing is actually installed. I recently undertook a major home extension, which required that the entire house, including the original part of the home and the extension, was a 5 star standard. I spent a lot of effort and time getting the insulation and sealing right. However, had I been lazy and not bothered to spend dozens of hours with a caulking gun and gap sealant, my house would still be classified as 5 stars because the design was certified as a 5 star design. The problem is that there is no mandated inspection to verify the quality of sealing and insulation. There are inspections for the footings and the framing, but not for the insulation and sealing. My building inspector didn’t even notice the effort I had gone to properly seal the sisalation around the windows. The home is certified as 5 star as designed but not as built. In effect its up to the builder as to whether they do the job properly or not. And considering that making sure that batts are not compressed and there are no gaps, and that all penetrations to outside must be well sealed is time consuming and costs money, why would a builder bother if there is no inspection to validate the quality of the work?

On the other hand the Australian Building Greenhouse Rating Scheme (ABGR) for commercial buildings is actually effective in reducing building energy use. The reason for this is that it is based on the actual performance of the building, based on one year’s worth of billing data. It cuts straight to the bottom line – the actual amount of greenhouse gas produced when operating the building. So the type of appliance (eg computers), the lighting, and the actual heating and cooling performance are all important to achieve a 5 star whole of building ABGR rating. These building genuinely use less energy, and produce less greenhouse gas emissions, than lower star buildings.

The bottom line when it comes to averting dangerous climate change is reducing greenhouse gas emissions. The residential 5 star standard isn’t achieving this, because it doesn’t focus on the bottom line – the actual energy use and greenhouse gas emissions of the home when occupied and in use.