Zero carbon homes need good tech and good tenants
Achieving zero carbon homes is going to need occupants committed to keeping down the energy consumption, as well as good design and a dash of renewable energy.
Looking at the prospects of achieving the goal, he summed up saying: "You can go genuinely zero carbon now but you have to have properly engineered buildings, people who are committed to it and a big space to stick up wind turbines."
He warned that less progress than might be expected has been made in this area, comparing the average energy use between a home from the 1970s and 2001 - pointing out that there was very little difference, perhaps as affluence and affordability of electrical goods outstrips good practice and improved efficiency.
"If you think that we've suddenly become vastly more energy efficiency in our homes, the answer is 'no we haven't'," he said.
He also said that there were some surprising gaps between the popularity of certain technologies and their effectiveness.
He pointed to research from South London looking at planned renewables and energy efficiency measures.
"The most popular were solar thermal, photovoltaics and to a certain extent heat pumps, but the most carbon effective were non-renewables - so they were combined heat and power and recycled heat and power.
"You've got an immediate mismatch there between the number of things people are putting in and their effectiveness."
Homes that effectively do the job for the occupant and require little or no action - such as Europe's Passivhaus movement - can make massive energy savings, but they are unlikely to ever reach the target of being zero carbon.
At the moment, said Mr Griffiths, that goal seems to require the householders to be engaged and keen - as in Nottinghamshire's well-known Hockerton development.
"The people in Hockerton are enthusiasts - they are people who love low energy living, that's why they're there.
"And to a certain extent they compete to see how little energy they can use. It requires some active engagement with the building. You have to be committed to it to make it work."
The biggest issue in this country, he said, was the 'spectacular' waste of heat.
Good insulation and better design for passive heat and light would likely outstrip renewable for some kind to come, he suggested.
"You can put on your on-site renewables but they are really quite small," he said.
"With the best will in the world they're not going to sustain the kind of lifestyle we're used to now."
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