wrote:
On 10 Dec, 12:31, David Hansen
wrote:

David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

I think you are being a bit generous with your payback times.
Insolation in middle England is about 0.1kW/m2 on average. A DIY solar
install is going to cost around 500 quid/m2, it's going to be at best
50% efficient. If you think 5p/kWh is a fair price, that means over 20
years to pay for itself. There's no way the system will last that
long, particularly if you use Navitron roof mounts.



Dave is a Believer. Facts will not alter his opinion.

The reality is that given a clean sheet of paper it would be possible to
design a house that maximizes every possible energy factor. Such a house
would be very efficient, but would be utterly unlike a conventional house.


Essentially I have in mind a 'hobbit hole', with about 6-10 ft of earth
over it, south facing double glazing ONLY, light pipes for internal
illumination, and a full heat recovery ventilation system.

Insulated to the hilt, and built of massive amounts of masonry.

This would be its own heat store (or cool store)

I'd use a heat pump connected to pipes buried in the earth roof.

Possibly photovoltaics to charge batteries to drive the pump.

The key though for house heating is to have huge heat exchangers on the
ventilation. Ventilation is the dominant heat loss in a super insulated
house. If teh heat pump heated incoming air (or cooled it in summer)
that would be the final tuning of the internal temperatures.


In summer, reverse the heat pump and drive heating coil in an outside
swimming pool etc. And refrigerate the house..

Needless to say this would be a very ecpensive house, and would take a
lot of energy to make...

In the end you have to do the cost benefit analysis on whatever you make
and amortize it over the expected lifetime of the house.

For urban situations, the answer is to essentially roof over a city
block. And use photochromic glass..