NHBC has just published a report on how the shape of a building changes the energy usage.

“When the basic results from SAP are fed into the Buildings Regulations compliance methodology which follows, the benefits of Form Factor do not register. The current Building Regulations in the UK are therefore unable to provide an incentive for industry to design and build homes that have a more efficient type and shape.”

See https://www.nhbcfoundation.org/wp-content/uploads/2016/10/NF-72-NHBC-Foundation_Shape-and-Form.pdf

Geodesic dome, anyone

Barney

http://www.domespace.com/en/home

one of these near me, maybe I ought to ask to visit !

gg

You can put interesting shapes outside of the thermal envelope, and use different wall surfaces to make the building look interesting. You can have as many roof overhands as you like without increasing the thermal surface.

Some of the examples in the report are 100 times better then most new builds in how they look.

Posted By: EasyBuilderAs designers our challenge is not just to build the most efficient shape, but to build a shape that meets our other human needs as well. As always, to find the best compromise between conflicting needs.

To even begin that, you have to understand the effects at all levels, to balance them ('compromise' is a dirty, politician's word - good designers do 'synthesis', which is quite different). By all means, go off-cuboid, but most designers don't understand the energy consequences.

Energy loss is normally related to surface area so from a practical point of view a square box gives you the most usable space (volume) for a given surface area.

However a sphere is the most efficient and actually has the greatest volume for the least surface area but not very useful when it comes to building usable spaces;)

Well actually a cylinder Tom ?

Bit like the dome building linked to above

Regards

Barney

Posted By: adiEnergy loss is normally related to surface area so from a practical point of view a square box gives you the most usable space (volume) for a given surface area.

It tends not to, as you have more wasted space with hallways etc, then you do with a "shoebox" shape, there is also the issue of how far you want the back of rooms to be from windows.

Combining

Posted By: joe90an oblong with the long side facing south was best

and

Posted By: barneyWell actually a cylinder Tom ?

If it's half a cylinder you are thinking of then maybe Nissen (of hut fame[1]) was onto something?



[1] https://en.wikipedia.org/wiki/Nissen_hut

Just to point out that while minimising surface area is one aspect of good energetic design, there are also other criteria, including for example solar gains. In our case it turned out that the most critical aspect was reducing the area of north-facing windows rather than the area of the south-facing ones or even the shape of the house..

However, with well insulated walls and adequate south windows the solar gain into the floors etc is useful as the solar gain stays within the envelope ( well I hope so as that's a principle of my build.🤓)

Posted By: DarylPPart L compliance takes no account of wall area, it uses the same shape for the notional/reference design.

Could you clarify what you mean by “same” there? Do you mean that it always uses the same shape for the notional design (what shape?) or that it uses the same shape as the designed house?

Building regs airtightness effectively uses the designed shape: it's m³/m²/h where that takes the m² as the outside surface area of the house so a house with a complicated shape is allowed to leak more overall.

Posted By: ringi"Best" is clearly flats and with modem standards of sound insinuation they can be reasonable to live in.

I think your definition of "best" is too narrow here; high population density brings with it all sorts of downsides

Posted By: DarylPI would suggest just the opposite..... as U-values fall/insulation levels rise, solar gain contributes a greater % of the (lower) heat demand.

Posted By: joe90However, with well insulated walls and adequate south windows the solar gain into the floors etc is useful as the solar gain stays within the envelope ( well I hope so as that's a principle of my build.

Most solar gain is in the summer were no houses in the UK needs heating, let’s discount this.

The next highest months of solar gain are in the spring and autumn.

Even a house build to Part L standards is unlikely to benefit from much solar gain at the start of the autumn, as it is gaining more energy from the people living there and electrical items, then it is losing.

As we get closer to passive home level, the house does not need solar gain in the autumn, it also does not need solar gain towards the end of the spring. There is very limited solar gain to be had in winter, due to the lengths of days and how little sun light gets to the earth even in the day time.

Hence energy modelling needs to be done on “day by day” bases using data from a few years, not looking at average heat requirements and solar gains.

I expect that in “real life” most homes don’t have much option for solar gain based design, as homes are put on both sides of roads, and road layout tend to be decided based on the shape of the land. Even avoiding windows on the north side of a house can be hard as people like windows to look over their garden.

Could you use permitted development to "fill in" with some extensions.....