Alan Pears explains why coal seam gas is not the answer and, when it comes to energy-efficient homes, why the cooling side of the equation needs some attention.
Coal seam gas (CSG) has been widely promoted as a game changer that will drive a gas boom. It’s not. It’s a desperate attempt to prop up the fossil-fuel era. It is also a conflict between the established energy industry (backed by governments) and just about everyone else, including state governments desperate to win votes.
However, the predictable failure of CSG will shift the balance in favour of sustainable energy: efficient, smart, renewable, distributed energy-service solutions.
The gas industry and the federal government are throwing everything at supporting CSG. Even the east coast ‘gas crisis’, caused by companies building natural gas plants in Queensland without locking in their gas supplies, has been used to try to justify more CSG development.
The reality of CSG
The CSG reality is that very large numbers of gas wells must be drilled and networks of pipelines built, conflicting with tourism and agriculture, placing underground water resources at risk, exposing people, animals and plants to toxic chemicals, and potentially leaking methane, a very active greenhouse gas.
In addition, the wells don’t produce gas for very long, and they must then be managed for an unknown period to limit impacts on the local environment and underground water resources. And it’s not cheap gas: in fact, high international prices are needed for it to be profitable.
The gas industry has blamed ‘cowboy’ operators for problems. But how do they respond when a responsible operator like AGL is found to have methane leaks from nearly a tenth of its CSG wells in NSW? (www.bit.ly/SMHCSG)
The NSW Chief Scientist has published a thorough report on CSG. While she finds it is possible to manage CSG responsibly, she spends quite a bit of her 24-page report outlining the difficulties in ensuring strong regulation and enforcement, funding to deal with problems during and after production from wells, and strong governance mechanisms.
It seems obvious that these requirements cannot be met by any Australian government. Voters know that no present government can lock in comprehensive environmental regulation and enforcement to ensure future governments manage derelict wells for decades or longer. We simply do not have the governance capacity to properly manage the long-term impacts of CSG.
CSG is more trouble than it’s worth. We have wasted too much time failing to address climate change to be able to enjoy the luxury of using fossil gas, especially leaky CSG, as a transition energy source. The global carbon budget is just too tight.
At the same time, technology development, economies of scale and emerging creative financing solutions mean that efficient, smart renewable energy solutions can deliver practical, lowest cost solutions.
While Australian governments and the energy industry wallow in denial, the International Energy Agency, World Bank and numerous leading economists have joined climate scientists and the sustainable energy industry to support this transformation and proclaim that it is practical.
As former Saudi oil sheikh Ahmed Zaki Yamani said in the 1970s (www.bit.ly/NYT-AZY), ‘the stone age didn’t finish for lack of stone’. We have now moved beyond fossil fuels, although we can acknowledge that they have provided a useful technological base on which we are building our sustainable energy future. The shift away from fossil fuels is reflected in the industry’s increasing difficulty in accessing capital.
Why do new energy-efficient houses need cooling?
Last year, CSIRO’s field evaluation of 5 Star homes reported some interesting findings. One big issue was a widespread lack of compliance, due to near-total failure of enforcement by governments and local councils. Another important finding was that, although the efficient homes had much lower heating energy use, their cooling energy use was not lower. The reasons for this outcome are complex, but it’s time we addressed them.
One reason may be that the default settings for cooling use in the NatHERS calculator seem to underestimate cooling. The thermostat temperatures and user behaviour patterns were set many years ago, based on quite limited information. Research has shown people typically use lower thermostat settings (see www.bit.ly/SETSACER). A 2008 South Australian study proposed changes, but these have not yet been formally regulated.
When estimated cooling energy is too low, it has little impact on the energy rating. In climates that require both heating and cooling, designers are more likely to focus on building features that reduce heating.
This under-emphasis on hot weather performance in the energy rating scheme means features like dark-coloured roofs and absence of eaves have unrealistically low impact on rated summer performance. In cooler climates, the overall annual outcome can even improve the Star rating, as benefits from more winter solar gain outweigh worse summer comfort!
The energy rating is also averaged over the whole building. So some rooms may perform poorly without adversely affecting the overall energy rating. And the rating is for total annual heating and cooling. Separate heating and cooling ratings would ensure the home performs adequately all year.
The nature of modern building designs is having its impact, too. The upper storey of a two-storey house has no links to the stable temperature of the ground, and is exposed to higher solar radiation. If glazing is not very carefully designed and managed, it becomes a ‘solar oven’—although the amount of energy required to cool it is not very large if it is well insulated.
More broadly, we need to realise that a high thermal performance home (with good insulation, draught proofing and well-designed glazing) requires very little additional heat to raise its internal temperature above the outdoor temperature—in both winter and summer. Extra internal mass or phase-change materials can help to stabilise the temperature, but climate change is increasing overnight summer temperatures and the duration of hot spells, so thermal mass is becoming less effective.
Careful design is increasingly important, especially glazing and adjustable shading, so that summer sun can be screened out.
Air leakage and poor management of ventilation is another culprit. When an exhaust fan or rangehood is running in hot weather, it is actually bringing in a lot of hot outdoor air—equivalent to a cooling load of 2 kW or so. On a hot windy day, having a window on one side of a house open, even a little, can combine with exhaust fans, fixed ventilation in a laundry or another open window on the opposite side or upstairs to create heat input of up to 5 kW. So, leaky open-plan homes with doors to permanently vented laundries and bathrooms left open can have high cooling costs. Improved building quality and user education are needed.
Of course, this does not mean that 5 or 6 Star homes are a bad idea. If they are built properly and well managed, their peak cooling energy requirements are small, and hourly cooling cost is low, especially when combined with a high efficiency (5 to 7 Star) air conditioner.
We need to further strengthen regulations and enforcement, sort out the under-emphasis on summer performance in the rating scheme and educate home operators. We should also take advantage of the feature in rating tools that allows an energy rater to look at performance of each room or zone during weeks of hot and cold weather. Then designers could identify and address problem rooms.
Also, summer is the time when a typical rooftop PV owner may have excess free electricity. Using some of this for cooling to be comfortable (especially once we get batteries to store daytime generation for evening cooling) need not create load problems for the grid.
Alan Pears is one of Australia’s best regarded sustainable energy experts. He teaches part-time at RMIT University and is co-director of Sustainable Solutions, a small consultancy.
This article was first published in ReNew 130.
This entry was posted on Sunday, December 14th, 2014 at 1:22 pm