How should we define an Extremely Low-Energy Home (ELH)?

There are lots of definitions of energy efficient homes indeed all new houses are "energy efficient" and many claim to be sustainable and/or "eco".

I would like us to have a go at the definition in terms of energy use so how about this

Energy efficient = above 120kWh/m²/y

Low energy is below this and down to

ELH (extremely low energy) = below 50kWh/m²/y

PLH (phenomenally low energy) = below 15kWh/m²/y

(Edited in after FT. Autonomous homes zero from outside sources )


Anyone like to tinker with the numbers?

Energy isn't the problem.

emissions

Posted By: Ed DaviesWot Steamy sed. Fossils, of course, plus particulates, nitrous oxides, sulphates, …

Energy from sources which involve those emissions is the problem.

Ah yes, agreed - but how far do you go?

How about things, from products, to buildings and cities, to grand infrastructure schemes, which at best try to minimise their addition to accumulating damage to the planet's environmental immune system, instead of being designed to positively assist the planet in cleaning up the mess we've already made?

"Energy from sources ..." which fail to achieve that, is the problem.

Agreed wholeheartedly

Posted By: fostertomJust how big a reduction in "producing most of the emissions and pollutants that we currently do" is needed, to reverse the present gross overwhelm of the planet's 'immune systems', some of which have already gone chaotic as a result?

I don't know, but I am sure that there are people that do.
The question should be along the lines of how much can we add to the environment without it affecting normal variations.
By this I mean that some areas have higher than normal woodlands, some have lower than normal pastures, some parts of the oceans are warmer than others, some colder. Also those same parts have normal variations, this may be seasonal, decadal etc.

What we don't know at present is 'what is normal', though conservationists will tell you otherwise. This is why we dig boreholes to see what has happened in the past. From the data I have seen there is a lot of variation, this makes it extremely difficult to work out what amount of emissions is acceptable.

Another way to ask a question is along the lines of a conservation approach. So 'Were we sustainable in the year XXXX'. Then we can can use existing and future technology to reduce our emissions of all pollutants to stabilise at that level.

As I have mentioned before, environmental change is not all about CO2e, land usage change may well be having the same effect, the two together is not a good combination, and we have the two together.
Then there are issues with 'local' pollutions i.e. uncontrolled storage and dumping of toxic waste, urban heat island affect.

If we take our lifetimes, I think that I would be quite happy with a year like 1975/76, cold dry winter, hot dry summer. If we knew that was going to consistent then we could manage out water supply to suit (it was because it was an extreme that we could not, not lack of resources).

So best ask someone that knows more than I do, all I know is that changing land and adding atmospheric pollutants is changing weather patterns and the climate.

Posted By: fostertomWhat would have to be done to facilitate re-establishment of damaged immune systems aka stabilising feedback loops?

Nothing, that is the whole point. If we tried to introduce what we think is needed, then we are tampering again. Just leave it alone and see what develops. I was lucky enough not to have to see urban slum clearance in the 1950's and 60's, but my partner did. She was amazed that within two years of knocking down an East London street that plants and wildlife had taken it over. Conservationists may not agree with this approach though.

Posted By: fostertomEven if the planet's immune systems could be restored to health, and pressure on them relieved so that had spare capacity to begin clearing up the accumulating mess we've made, how many millennia would that natural cleanup take?

All depends where you want to end up. Do you want the patch of land that the oil refinery sits on to be the same as it was before the refinery or how it was 1000, 2000, 10,000 years before. Or do you just want it to look 'natural'.

Posted By: fostertomWill human life be able to hold out that long, in an environment that will continue to get nastier and nastier before it begins to get better?

Yes, but then I am an optimist.

Posted By: fostertomThese are questions that the world has barely begun to look at

There are tens of thousands of people asking this professionally, and millions asking it out of concerned interest. So not a case of barely started. I read an interesting bit in my comic a week or 3 back about the best way to tackle environmental change. The gist was that rather than think globally i.e reduce CO2e or we are all doomed and the coral will die in Australia, we need to think and act locally i.e do we want a wind farm rather than another mobile phone shop in our high street.

Scientists can put numbers on things, they can show the most likely effects of changing variables, they can show cause and effect, what they cannot do is educate the worlds population to change expectations and behaviour. That is what economists and legislators have to do. So at the moment we are slowly bring up the less developed parts of the world to a higher standard of living, while slowly reducing the developed worlds (what a recession does). Where it will stabilise I do not know, or what decade in our recent history it will be equivalent to. I don't even know the best way to get there. What I do know is that we will stabilise somewhere and cope with the normal variations in weather both in the UK and globally, we are doing a pretty good job of 'surviving' now, just as we have for the last 4 million years or so.
Yes there will be false dawns, mistakes and even catastrophes along the way, I think that I am right in saying that Spanish flu killed more people that the 1st World War, but in percentage terms of global population both were minor (though each could be a personal tragedy).