Room Temperature

Everyone seemed shocked that I could live in a flat with a room temperature of 11°C (52°F).

But 60 years ago, I’d guess that most houses were like that. 60 years back, as a small boy living in my grandfather’s house, most of the rooms weren’t heated. There were a couple of small coal fireplaces in two of the rooms. Maybe the house had cavity walls, but it certainly didn’t have double glazing.

It was like an icebox in winter. And quite often at dawn ice had formed inside the windows. It was an ordeal to get out of bed in the morning, and put a sleep-warmed foot down onto the ice-cold lino floor by the bed, and take off my pyjamas and dress quickly in thick underwear and socks and pullover, and go downstairs to the steam-filled kitchen where the porridge was being boiled. While outside the steamy windows birds fought among themselves for bacon rinds that had been thrown out onto the snow.

By that time of day, my grandfather had usually started making the fire in the small living room, twisting up newspapers and stacking them on the grate, piling split pieces of wood on top, and then lighting the newspaper. And sometimes it wouldn’t light, and my grandfather would repeat the process, sometimes two or three times, while I sat shivering at the table, gulping down hot porridge and milk and golden syrup.

By the time I’d finished, my mother would have usually managed to get a fire lit in the second small living room, and would maybe have switched on the coal-effect electric fire just for a few minutes, “because electricity is very expensive”.

It took ages to firstly light the coal fires, and then ages for them to reach their golden red working temperature, and even longer for them to warm the room. It must have been an hour or two before the room warmed up too. And during that time, if you sat too close to the fire, you got burned on one side and frozen on the other.

All the internal doors in the house were kept firmly closed, and the windows shut. And the result was that there were only one or two warm rooms in the house. The rest of it stayed ice cold all day, including the bedrooms and hallway and stairs. Rule Number One was: Close The Door!

With all those closed windows and doors, you might imagine that there was quite a fug inside. But there wasn’t. And that was because the coal fires and the gas cookers all had chimneys which sucked air out of the house. A coal fire generates about 20 air changes an hour. The air leaked in through the windows and doors. So when my grandfather lit one of his unfiltered Players, it didn’t fill the room with smoke. The room only filled with smoke when the wind blew the coal smoke back down the chimney, which it regularly did.

We lived very active lives. My grandfather would go outside in all weathers, to bring in coal or wood, or clear snow from the drive, or mend something. And, when the snow got too deep to use his little car, we’d walk the mile or so up the road to the small grocery, and maybe a further mile into the village where most of the shops were. And then walk all the way back, laden with bags, our feet and fingers numb.

It was only when you’d just got in from going outside that you needed to head straight for the fire, and warm your hands and feet in front of it, and gulp down hot, sweet tea or new-fangled instant coffee. After that, you didn’t need to stay right next to the fire. But you had to wear warm clothes the whole time.

So I’d guess that most of the house room temperatures were around 10°C, and I doubt that the living room ever got far above 20°C.

Keeping busy is a good way to stay warm. It was something that was brought home to me when I was a university student, and in winter I used to regularly walk a couple of miles to the university from my hall of residence, wearing just jeans and T-shirt and jacket. But I had to walk fast. And the colder it got, the faster I had to walk. One day it was so cold that I was almost running. But I couldn’t stop to catch a bus. If I’d stood at a bus stop, even for a few minutes, my body temperature would have started dropping rapidly. So I had to keep walking.

These days the coal fires have gone, and the rapid air change rates that came with them have gone too. And the double-glazed windows are more or less sealed shut. And the cavity walls are filled with foam insulation. And the lofts are insulated too. And so air change rates in modern houses are probably down to 1 or 2 air changes an hour. And in such environments, a malodorous fug can rapidly develop. And that’s probably why smoking (and indeed any kind of smoke) has gradually become more and more intolerable. And it’s also why ‘Body Odour’ has also become intolerable, and many people shower several times a day. Some people can’t even stand perfume either. Next they’ll start complaining  about the stench of coffee, and newly-baked bread. And if these various phobias have filtered down from the upper social classes to the middle classes, it’s because it was the upper classes that installed installed central heating and double glazing first.

It may also begin to explain the modern ‘obesity epidemic’. If you live in a cold environment, of say 10°C, you are losing heat to it at a higher rate from your 37°C body core than you are when you live in an environment with a temperature of 25°C. The rate of heat loss is K.(T1 – T2), where K is a thermal conductance equal to 1/R, and R is the sum of body and clothing thermal resistance. Whatever value K may have, in a 10°C environment the rate of heat loss will be K.(37-10) or 27.K, while in a warm environment it will be K.(37-25) or 12.K – two times less. So in a warm environment people usually take off clothes to increase the value of K. Either that, or they eat less food. But both clothing and food are highly culturally determined, and people don’t readily dispense with either the clothing they are accustomed to wear, or the foods they are accustomed to eat. So most probably a lot of people who are living in these warm, centrally heated modern homes are continuing to wear what they have become accustomed to wear throughout their lives, and to eat the foods that they have become accustomed to eating, in the quantities they have customarily enjoyed. And if they do this, they’ll be taking on board twice as much food energy as they actually need. And some of that will get stored as body fat, which also acts as thermal insulation. Unless they go jogging, of course, which is another way of burning off the excess energy, and something that’s only started in recent decades.

And back in the 1950s, the breakfast that I gulped down consisted of porridge oats with golden syrup, followed by eggs and bacon and tomatoes and toast, accompanied by toast and butter and marmalade, and hot tea with milk and sugar. That’s a pretty high energy breakfast. And then a few hours later there’d be lunch which would probably consist of roast lamb, boiled potatoes, carrots, and peas, followed by crusty apple pie and custard. And then a few hours after that there’d be tea, which would consist of numerous cups of tea, accompanied by biscuits and cakes covered with icing sugar. And in between all these meals, there would be the occasional bar of chocolate or sticky toffee or mint humbug. It was a high energy diet, with most of the energy pumped in at the start. But I remained as skinny as a rake, and so did my grandfather, and my mother and my brother weren’t much wider. And that was because we lived highly energetic lives, living in a cold environment, and walking or cycling everywhere.

And now I’m just living in much the way I lived 60 years ago, in the same cold environment. And eating many of the same foods too. Even keeping a window open to make the air change rate rise. But I eat very sparingly. Because I’m not living a highly energetic life.

Yet if I go out to lunch at a pub-restaurant, there will be a starter course that may be soup or something, and then there’ll be roast beef and Yorkshire pudding and roast potatoes and peas and carrots and gravy, and finally there’ll be a hot sticky chocolate cake dripping with cream. And it’ll all be washed down with wine or beer. And it’ll end with coffee and mint chocolates. And that’s just lunch. And it’s enough food to keep me going for two days. But, because it’s available on the menu, I guess that most customers are buying all three courses. And they’re eating full breakfasts and teas as well in their well-insulated, centrally-heated homes.

It’s not that there is anything wrong with eating lots of food, or living in a warm home, or doing very little exercise, or wearing currently fashionable clothes, or anything else. But these all have energy consequences, and it’s very easy to create an energy imbalance if you do all these things at the same time.

This isn’t about nutrition. Nor is it about chemistry. It’s just simple physics.

I think I’m going to dust off a few of my old books from back when as a university research assistant I used to build heat flow models of buildings. We had people in those buildings, but they were just heat sources. I think I’ll build a computer heat flow simulation model of a little house or flat, but I’ll also model the people inside them with their 37°C body core temperatures, and their body fat, and their clothing, and the food they eat, and the things they do. And maybe I’ll build a simple climate simulation model over the top of it as well.