"NickW" wrote in message
om...
The Building Structu
- A light framed superinsulated structure (Minimum of 400mm of Warmcell
in
the roof, 250-300mm in the walls, heavy foam in the floor if a concrete
slab).
- Face the house south to capture passive solar energy.
- Calculate the pitch of the roof for maximum insulation at your
latitude.
- Calculate the roof overhangs to keep the sun off the windows and walls
in
summer.
- Have the north side with few windows.
- Triple glazed with low "e" glass.
- Eliminate thermal bridges. These tend to be where the walls meet the
ground and the roof, or one material meets another. Use nylon tie bars
if
cladding in brick
- Use SIP panels or TJI "I" beams. The void in the "I" beams can be
filled
with Warmcell cellulous insulation (re-cycled newspaper). The Warmcell
makes
the structure air-tight.
- Have all of the south facing roof being a solar panel heating water
from
the sun. That is a large surface generating much heat.
- Could have a full width conservatory on the south side. Better if full
width and full height. This will help but not essential. Nice to have
though as bedrooms could have a balcony opening into the conservatory.
- No letterbox in front door. All doors heavily insulated and sealed
(the
Swedes do the best doors).
- Specify a study for home working.
Heating, Vent, Thermal Storage:
- Store the heat in a large thermal store, which would have to be sized
to
suit. Better have a battery of small cylinders, so if one leaks it is an
easy and cheap job of replacing.
- The heavy thermal stores can be at ground level. They could even be in
a
separate building with superinsulted underground pipes between it and
the
house if need be. The thermal store should hold enough energy to heat
the
building over 3 or 4 cloudy days.
- Use "very" low temperature underfloor heating.
- In winter not a lot of very hot water will be generated, but hot
enough
for very low temp underfloor heating.
- This low temperature water can act as a preheat for DHW.
- If hot water is generated, hot enough for domestic hot water, then
this
water should be suitably stored for ready use rather than merging into a
large low temperature water store.
- The controls will be off the shelf and all be using the odd pump here
and
there.
- A backup heat source can be incorporated when cloudy days extend over
3 or
4 days.
- The water system is understandable by any intelligent plumber.
- As underfloor heating is being used, bets have an extract only vent
system. Heat recovery is expensive. The thermal store should store
enough
energy for the heating system to compensate for vent losses.
Water reclamation:
- There are large water tanks that fill from the roof available ready
made.
The BENELUX countries have these as standard in new builds.
- The water tank is under the garden.
- The water is used to water the garden and flush toilets, reducing
water
consumption drastically.
PV Cell:
- Don't bother as they are still super expensive with very long payback
times. If the hosue done as above then little elecricity will be used.
Low Energy Appliance:
- These tend to be German like AEG, etc. Find out which of these is the
most economical in energy and water consumption and put these in the
spec.
Comms:
- Wire the place out in CAT 5 to accomodate computers and home working.
The above is the basic concept. Then, depending on site, size of house,
etc,
it is a matter of applying numbers to size up the thermals store, heat
loss,
How much energy the solar roof will generate, sizing a "very" low temp
underfloor heating system, etc.
Best of luck. I hope you get it and you build the house. We need more
people
like you around.
Some good stuff there. Just one thing though,
the walls are the best solar collectors (for space
heating) due to the angle of the sun in
winter.
A full south facing roof as a solar collector, angled correctly is as good,
and the walls are not impeded by glass. The house can then look pretty much
how you like it. The roof can be angled to the optimum angle on the south
side and at a shallower angle on the north side, which allows cold north
winds to blow over the house more easily.
So you'd have small windows on the south side too but the
walls would be built using glass on the outside (or maybe
polycarbonate), and a black collector surface behind. The heat that
builds up here would (by convection) be collected in another cavity
behind the first wall which contains drums of water as a thermal
store.
This article on solar closets explains it better than I can:
http://www.ece.vill.edu/~nick/
I am not that enthused, although I'm sure it works. It is an air system,
nothing wrong with that, operating by gravity. This restricts the house
design. You need an expensive strong structure to hold all that tonnage of
water in the loft. That ramps up build prices. So straight away two
problems.
Solar air heaters get very hot and scorch marks occur at the top of them
which makes them unsightly. Storing the thermal mass (water in large
cylinders) at ground level is cheap in structure costs, and using a large
full roof solar collector means you have house design freedom. No large
glass areas on the walls.
Storing the heat in a thermal store and then pumping it into a "very low
temperature" UFH system means you have far more control of the comfort
conditions. No far too hot or far too too cold situations. You can also
use a conventional boiler to heat the UFH directly (do not store its heat in
a large thermal store) when the thermal store is exhausted of heat after a
week of cold cloudy conditions.
The problem with passive solar designs is that you live inside the heat
generator itself, so it can get a little too hot inside the house at times.
With my spec you don't even need to us passive solar as long as
superinsulation is used, as the heat is stored and used as you dictate. But
using passive solar is a great bonus as should be used. Shades can go some
way to preventing unwanted heat entering the house. Although this situation
would be very rare as the roof overhangs would take care of unwanted sun in
summer. It has been said that all house are solar houses as all have the
sun on some part of them. It is a matter of harnessing that sun. This could
be via a solar attic in some houses that do not have a south facing
elevation.
The spec I have outlined is cost effective and easy to build using materials
that are cheap and readily available with ready available skills that can
also work with them. It is a matter of getting the "design" right, which is
not expensive at all, and can be zero cost.