Energy Matters Forums

[moemoke]

I work for a small engineering company doing structural design for houses etc and as such I get to look
at a lots of Building Designers plans, Since the 5 star energy rating was introduced a few years ago there was a lot of talk that not many houses would comply and it would cost to much to build anything with more than 5 stars. I have noticed an increasing number of houses with more than 5 stars but they have no special features to get this figure, one I'm working on at the moment has no eaves, no double glazing, the long side of the house (2 bedrooms and family room) faces North-West. I think this house would be like an oven in summer but the Accredited Rater has given it 6.2 stars .
The house was rated with the 'first rate' program which I know is not as good as what some of the other states use but in Vic it's the main one used

Also who checks that a house has heavy curtains or door seals etc installed and maintained so that the house
meets its so called star rating for the life of the house.

Does anyone have any experience with the rating software or other knowledge of this so called 'star rating'

[PeterReefman]

Yep I agree Moemoke.

I built my first offical 5 Star back in '95 when Energy Vic (as Sustainability Vic was then called) was still working on the system.

The house was orientated and zoned to be true north, R4 Roof - R2 external wall insulation, with double glazing in all the living areas, 800mm eaves to the North, no west or east windows. In short as much as I could throw at it at the time (with my still-limited experience in those days). It scraped in with a rating of 5.1 Stars.

So yeah it frustrates the hell out of me to see the rating watered down so much since then. But there has been a fundamental shift in the system when it went to 10 Star maximum. The scale is based on MJ per M2 per year, and in Melbourne 0.5 stars (the lowest on the scale) is 676MJ-M2-Yr, while 10 Star is 2MJ-M2-Yr.

The difference from 5 star (149MJ-M2-Yr) to 6 star (114MJ-M2-Yr) is isn't a huge amount and improving in that range is relatively easy, FAR easier than going from 7 Star (83) to 8 Star (54).

http://www.nathers.gov.au/about/pubs/starbands.pdf <-- Complete star rating details

You're right about a 6 Star house being potentially crap in the real world too. The software is obviously a simulator and often that simulation is inaccurate because of intangibles (although a NW orientation should NOT be an intangible...).

Speaking of inaccuracies in the system, it doesn't always err to the side of a beter rating either. My own house offically rates 8.1 Stars, whereas in reality it consumes about $15 of artificial heating and cooling energy per year, which for the size of this house would give it a 9.7 Star rating. But I can't call it 9.7 because the official rating is based on the simulation, not the real world...

By the way even though policing can certainly be an issue, curtains aren't part of it. Even though you can specify heavy curtains in the software, the 'official' rating will ALWAYS assume holland blinds (again, my own house has thick insulating roman blind with integrated pelmets which perform FAR better than open-top holland blinds which contributes to my inaccurate rating).

With the current software we should be aiming for 7 Star minimums, and the simulation engine should be being constantly refined/improved by entering real world performances/corrections as the respective houses are completed.

One other thing, have a look at this presentation from ABSA, which demonstrates the thinking of using loopholes to get to 6 Star without needing to design for passive heating/cooling. And yes it's for new houses, not retrofits.
http://www.absa.net.au/files/public/News/Presentation%20by%20Wayne%20Floyd.pdf
The key message is "6 stars on any orientation is inexpensive with 2nd generation Building Thermal Performance tools"... To be fair it does also say that the key to 7 Star is to design around orientation, but the overall message I think is one of cheating the 'system'.

I closing, the good news is that it looks like we might see a new national minimum standard of 6.5 Stars, which will hopefully see a little more than those "Any orientation workarounds" we're currently seeing.

Cheers,
Peter

[Susbility]

The whole so called star rating system is nothing but ticking boxes to get the wanted star rating, is has little to do with good building standards, just wraping the house with a foil wrap is just nonsense to get a 6 star rating, we need building standards like the Europeans have, properly designed well insulated walls walls, brick verneer contruction is the pits for heat and cold transfer, roofs that are not insulated are a real problem, roofing tiles in very dark colours like black, dark brown etc act like heat sinks, it just can not understand why we keep building with dark bricks, the whole housing building code needs to be redesigned to maximise insulation agains heat and cold penetration. In a properly designed house the temperature should never vary more than 10 decrees C and no need for airconditiong.

[Solarmark]

PeterReefman, just wondering where you got your thick insulating roman blinds from?

Cheers
Solarmark

[PeterReefman]

Hi Solarmark

We just asked our local curtain maker to make them up for us, from a fabric of 50% hemp, 50% organic cotton that we organised. This was stictched over regular thermal lining.

The shop (http://www.bedazzledonline.com.au) was a little uncomfortable with our face fabric as they thought it may fade and shrink badly. We took the risk based on Low-E coatings on the windows would reduce UV penetration, and we were comfortable that temp/humidity levels in the house would be stable enough to keep things... stable.

A year on there has been some fading but not enough to be a problem, and the fabric hasn't shrunk/stretched/distorted at ALL. So it worked well.

Performance wise, I honestly think they're a BIG part of why the house has only used about $6 of heating so far this year, which means it's performing WELL above it's official 8.1 Stars. In fact, the $6 figure is more in line with a 9.7 Star house. (high quality blinds are not allowed to be included in official energy ratings, which is a huge omission in my opinion because they are fixtures which can clearly make a massive difference.)

Hope that helps.

[PeterM]

http://www.absa.net.au/files/public/News/Presentation%20by%20Wayne%20Floyd.pdf

This presentation is no longer available Maybe too controversial

[conklinc]

The building codes definitely need upgrading. I'm from the States and bought a 2 bdrm unit that is nine years old. I was appalled at the paltry amount of cellulose insulation in my ceiling. First thing I did was double it to 8 inches/20 cm. What a difference. One time cost to protect me against constant natgas price increases. The external doors were shocking, drafts top, bottom and sides, quickly eliminated by weatherstripping. Last spring we were shocked by the heat coming through the three north north west facing windows . . . so up went retractable canvas shades. We plan to replace the Vulcan wall furnace . . . assuming we can get a high efficient 93+% one with no pilot light. Also planned: a 3kWh solar voltaic system (our use average is about about 7kWh per day, year round) We're gone in January and February so all the juice will up grid.

When you are retired and on a fixed income, it is important to take care of heat loss in the winter and heat gain in the summer. Generally speaking, those are one-time costs for lifetime savings.

Question: I note the Vic solar up-grid tariff law indicates the program is to last until 2024 and is only good for a total of 100kW added over the whole state. How long will it be before the 100kW are bought up, at current rates of installation? What about other states?

Oz is light years ahead of the U.S. in terms of creating solar incentives and rate of installs. I just wish we had Yanqui prices for the panels and inverter.

[CarbonetiX]

The problem with the five star energy rating is it isn't actually an energy efficiency rating, it's a predicted relative thermal efficiency rating. Like Peter mentioned because it's simulated the rating often doesn't reflect the true thermal efficiency of a building. There's problems with the inspection process as well, in that there is no point at which the inspector verifies how well insulation has been installed. If you have insulation batts that are compressed, torn or have gaps this can lead to a lot of heat loss.

Those issues aside the biggest problem with the rating system is it only attempts to predict energy required for heating or cooling. It doesn't take into account the energy used by lighting, hot water systems or appliances. This means that if you take two otherwise identical homes, but outfit one with a large number of inefficient lights (such as halogen down lights), they will still receive the same rating despite the fact one will clearly consume a lot more energy.

Ultimately this rating can be misleading to home buyers who think they're getting houses that are much more energy efficient than they really are (Especially if they're not as well informed as the people on this forum).

If you're interested in reading more we've written more about the energy rating here: http://www.carbonetix.com/why_your_5_star_energy_efficient_home_isnt.php

[conklinc]

So the five star rating is half done, lacks teeth in the area of
energy efficiency and lighting, as well as insulation inspection.
I know where I am from in the States, there is a mandatory
inspection of insulation before the "drywall" or gypsum board
goes on.

Another thing, furnaces and air conditioners vary in efficiency
too. A good, energy-efficient home will have both good
insulation, efficient lighting and efficient heat/AC and appliances.

I read you website, interesting and valid points. I am of the
opinion that that Australian insulation standard is woefully
inadequate. Melbourne's weather and climate compares to
San Francisco, yet the ceiling insulation standard is half. I
added an addition 4 1/2 inches of cellulose insulation in my unit
this winter and noticed the difference the day it was installed.
Now I need to shield my recessed lights not halogen) and get
rid of he cardboard box fences around them and put more
insulation much closer to the shielded light fixtures. I don't
like recessed "can" lights, but at least I don't have the crazy
halogen lights that give off less light and consume more energy.

Thanks for your response.

[caleb]

I am a registered energy rater using firstrate 5 here in Victoria, and while I admit the rating system can be misleading to the average person (for reasons mentioned earlier in the thread), I just want to point out the reason why the star rating only takes into consideration the estimated thermal performance of the building. It is because the rating is intended to remain constant throughout the foreseeable life of the building, independent of appliances and fixtures that may have a shorter life span or which may be replaced or used differently by various house owners.

I guess the government opted for this relatively simple approach as to avoid further confusion and the need to update the energy rating periodically, or every time something is changed within the house.