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Wednesday, 21 November 2012

Local warming



Our house is one of those 1930s bow-fronted houses you see all over the place. It faces East/West so the rising sun is captured by our bow windows at the front and the setting sun illuminates our kitchen and the room at the back where we have our wood-burner.

What still surprises me is how much warmth we get through those bow windows on a sunny day, even at this time of year. The morning sun can warm the front room from an overnight temperature of say 15°C to 19°C in a couple of hours – which is at least as quick as the gas fire.

It’s similar at the back of the house where large windows facing South and West gather warmth from an afternoon sun. A sunny day with an outside air temperature of 10°C warms the house while on a cloudy day at the same temperature we receive no perceptible heat at all. It all makes me very aware of the importance of cloud cover. We all know about that anyway, but the confusions of modern times sometimes pushes these basic experiences into the background.

Our back room is an interesting room in that it is small and very easy to heat. Other things being equal, the size of rooms is important as we get older, because for obvious reasons, smaller rooms are more easily, quickly and economically heated. 

The back room was once a typical 1930s dining room, accounting for its small size. We don’t use it as a dining-room because we always eat in the kitchen.

Anyway, the whilom dining room has a large central heating radiator. When we switch the heating on, it can warm from an unheated temperature of 14°C to 19°C in about an hour. If I light the wood-burner at the same time as turning on the heating, then after an hour the central heating can go off and we have a room warm enough to sit and read.

The front room is only about 25% bigger in floor area than the back room, so maybe other factors are involved, but room size seems to matter when it comes to keeping warm on a winter’s evening. No, we’re not planning to downsize as we only moved a few years ago. We seem to be well situated in that the house works well for us, but for older people the issue is worth thinking about. 

Small rooms are easy to heat.

The really obvious examples of gains made by heating smaller spaces are beds and clothing. In the UK, is easy enough to stay warm in bed overnight in an unheated bedroom, simply via good insulation and body heat. If the volume of trapped air round the body is small enough, body heat will do.

The same goes for clothing. Last winter we set off walking in a temperature of -7°C, which in many countries is nothing special, but the UK counts as pretty chilly. We have the right clothing for these conditions and after about a mile or so were warm and comfortable, even up in the hills. It was still well below freezing when we sat down for lunch, but if you have the kit it isn't a problem.

So why don’t we just wear outdoor clothing all winter, even in the house? Partly because it’s uncomfortable I suppose, and partly because in the house we aren’t generally moving around enough to generate sufficient excess body heat.

So I’m sure we could do more about housing design and the advantages of smaller rooms, especially for older people. It’s not so much about saving energy as making the best use of things we already know perfectly well. It's a pity that house size tends to be correlated with social status.

8 comments:

John Page said...

Give me cosy rooms any time, rather than those characterless open plan spaces.

A K Haart said...

John - yes indeed. We call our room "the snug" because during the colder months it is.

Woodsy42 said...

We too have a large south-east facing bay window and as you say the sun on a cold but clear morning produces as much heat as the radiator. More so than in the summer as the winter sun is lower and penetrates across the room.
It's the simplest cheapest form of solar heating and yet houses are almost never built to take advantage of it, being built in rows without regard to direction of overshadowing by neighbouring properties.
On room size I have mixed feelings, I love large open rooms and could cheerfully remove all the house's internal walls to have just a large space. Small rooms are claustrophobic, so there has to be a compromise between size and winter heating needs - or we heed much more flexible house layouts.

Macheath said...

I think I'm right in thinking that the trend for open-plan homes came from the US - land of low energy bills, maintained furnaces for heating entire apartment buildings and cheap, abundant firewood in rural areas.

Scrobs... said...

We've had storage heaters for 23 years, and with one open fire to do as you say, give you a boost when you need it, they're extremely good, and not expensive!

A conservatory can go up to 90 on a normal summer's day though... I wish I could store that for January!

A K Haart said...

Woodsy - the only large rooms I like are baronial halls - but we don't have one of those!

Mac - it did and it was never suited to the UK in my view.

Scrobs - I've been looking at storage heaters. With modern electronic controls they sound interesting.

James Higham said...

I'd always have bow windows - they're superb for the mood too.

A K Haart said...

James - ideally I'd like an oriel window, high up with a view and a window seat.