[permaculture] Energy-efficient, low maintenance, durable building design.

Lawrence F. London, Jr. lfl at intrex.net
Sun Oct 1 21:36:11 EDT 2006

As with residential home construction so with institutional, commercial and industrial - architectural energy efficiency 
is easy to achieve when using many of the currently available, refined, high-quality building materials, some new, some 
traditional, in the design specs.

Consider FL Wright's Prairie House, earth-bermed structures, simple in design, using a lot of concrete, all on one level 
and very stable and  durable. Houses can be built on multi-level (to accomodate changes in existing grade) monolithic
slabs or grade beam slabs of 6000 PSI fiber/rebar/wire-reinforced outdoor concrete. On this lay an exterior wall of 
heavy ornamental or architectural 8" concrete block, "split-face" has one side that looks like stone; this is your 
structural, load-bearing wall. These kind of blocks are often available as overruns for $.75-$1.00 each, less delivery. 
Prior to laying this wall you can embed threaded anchor bolts in the slab so that tension rods can be inserted through 
the wall cores and connected to these bolts; the tension rods are then connected to rebar or some other steel bar or 
beam running horizontally along the top of the wall. Premanufactured steel trusses can be mounted along the top of the 
wall and tied to these tension rods. Steel studs can be screwed or welded across the trusses as purlins and heavy gauge 
prepainted steel roofing can then be attached to trusses and purlins. Allow a 2" air space then lay a core wall of AAC 
block (Aerated Autoclaved Concrete available from Aercon in Florida and Hebel in Georgia) next to the exterior block 
wall for insulation, the thicker the block, the higher the R-Value - they start at 8" and go to 16", maybe 20".  An 
interior wall, also of heavy ornamental 8" block, is laid next to the AAC block wall. A finished wall of this sort can 
be as much as 42" thick. As for the floor, 8" AAC block is laid across the entire floor area leaving 4-8" gaps along the 
walls and within the interior of the floor on a grid of channels for support beams for the finshed floor. Interior-grade 
concrete, 6000 PSI strength, wire and rebar-reinforced, 6-8" thick is poured over the entire floor area. The roof can be 
insulated with 12" to 16" of high-density hard-forming plastic foam insulation. Reinforced AAC curtain walls are 
available from the suppliers 4' wide to as much as 20' long and 4-6" thick. These prefab units can be used as floors or 
room dividers. Apply stucco or paint and you have a nice looking ceiling or wall. They are also used as integrated 
roofing and insulation and for this application they are offered T&G, as far as I know. As for heating and cooling, a 
house built this way will have lots of thermal mass to recycle heat from solar or heater and cooling by closing doors 
and windows during days and open sometimes at night. I expect annual energy costs to keep inhabitatants confortable 
would be very low. As far as active cooling and heating is concerned I hear that hydronic cooling systems, hydronic heat 
pumps and conventional heat pumps have gained in efficiency and might be worth considering, especially underground 
piping circulating 50 degree water through a heat exchanger. H.S. Tarm, a Danish wood stove manufacturer makes several 
units that are the best in their class. The simplest is a wood-fired boiler that delivers very hot water to a large 
insulated storage tank with heat exchangers that deliver DHW and hot water for a zone-type radiator system throughout 
the house. Preheat your cold water input with solar and you add to system efficiency. The huge windowsills in this 
house, one to last hundreds of years almost maintenance-free, can be used to grow flowers, house plants, fruits, 
vegetables and herbs as well as for starting seedlings for Spring planting in the gardens.

Lawrence F. London, Jr.
Venaura Farm
lfl at intrex.net
info at market-farming.com
Venaura Farm, sustainably-grown produce & garden handtools
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