How to keep your home warm

Lesotho Times - - Property - Roland En­nos

IF you live in a poorly in­su­lated home, and many of us do, you could spend thou­sands this win­ter on en­ergy bills. But our an­ces­tors had many ways to keep snug at lit­tle or no cost. Now, thanks to mod­ern in­frared cam­eras and ad­vances in en­vi­ron­men­tal physics, we can un­der­stand how these meth­ods work and mea­sure how ef­fec­tive they are.

The key to un­der­stand­ing how to keep warm is the fact you lose more heat by ra­di­a­tion to your sur­round­ings than you do by con­vec­tion to the air. This is why your house feels so cold when you get back from a win­ter break, even af­ter you’ve turned on the cen­tral heat­ing; though the air quickly warms up, the walls take far longer to do so and may con­tinue to make you shiver for up to a day.

In the same way, in poorly in­su­lated houses the in­side of the ex­ter­nal walls can be sev­eral de­grees colder than the air and the in­ter­nal walls, mak­ing you feel chilly.

For­tu­nately, there are five sim­ple ways to over­come this and min­imise your en­ergy bills.

Close your cur­tains at night Dur­ing the day, your win­dows let in more ra­di­ant en­ergy than gets out; sun­light can en­ter through the glass, but the win­dow is opaque to the in­frared ra­di­a­tion try­ing to es­cape. At night, how­ever, sin­gle-glazed win­dows can get ex­tremely cold – in my Vic­to­rian house which we try and keep at a room tem­per­a­ture of 20°C, an in­frared cam­era showed in­ter­nal win­dow tem­per­a­tures of as low as 7°C on a frosty night.

Even dou­ble-glazed win­dows aren’t great in­su­la­tors and can fall to around 14°C. This re­sults in en­ergy losses of 50-100 watts per square me­tre, equiv­a­lent to run­ning an old­fash­ioned light bulb.

The best way to pre­vent this heat loss is to close your cur­tains and lower your blinds im­me­di­ately af­ter dusk. They pro­vide an ex­tra bar­rier to ra­di­ant heat loss, add in­su­la­tion and re­duce draughts. My cheap blinds raise the in­ter­nal sur­face tem­per­a­ture to 16°C and thick cur­tains raise it vir­tu­ally to room tem- per­a­ture, min­imis­ing heat loss and mak­ing the room feel cosier.

Cover your walls Solid brick or stone walls are bet­ter in­su­la­tors than glass, but they still get cold and let out lots of heat. In my house the ex­ter­nal walls fell to 16-17°C, 3-4°C cooler than the air in the room, even though they were made of 50cm thick sand­stone.

For­tu­nately you can sig­nif­i­cantly re­duce en­ergy losses by cov­er­ing them with pic­ture or mir­rors. Even a sim­ple poster adds an ex­tra layer of in­sult­ing air, rais­ing in­ter­nal sur­face tem­per­a­tures by around 1°C and cut­ting lost en­ergy by a quar­ter. Framed pic­tures or mir­rors are bet­ter, if more ex­pen­sive. Not be­ing a Rus­sian oli­garch or a me­dieval baron I don’t have any car­pets or ta­pes­tries to hang on my walls, but these would be even more ef­fec­tive.

Best of all are book­shelves. My part­ner is an avid col­lec­tor and her old books make su­perb in­su­la­tors. The spines of the vol­umes in our book-lined study are raised al­most to room tem­per­a­ture, mak­ing it snug and warm. Ther­mally at least, printed books are far su- pe­rior to their elec­tronic coun­ter­parts.

Cover your front door Doors can let in draughts, and be­ing thin and some­times glazed can be very poor in­su­la­tors, fall­ing to 10-15°C on cold nights. Cov­er­ing your door and the sur­round­ing wall with a thick lined door cur­tain can elim­i­nate pretty much all the heat loss.

Use screens Even if you can’t re­duce all the heat loss from your outer walls you can still shield your­self from the cold. Our an­ces­tors used to draw up wooden screens be­hind them­selves and hud­dle up to the fire. Be­ing at room tem­per­a­ture, the screens kept their backs warm, while ra­di­a­tion from the fire heated up their front. You could do the same, and you could even pro­tect your face from the dam­ag­ing ef­fects of a roar­ing fire by us­ing minia­ture fire screens, just like Ge­or­gian ladies.

Po­si­tion your fur­ni­ture in the warm How warm you feel in a room de­pends on where you are, even though air tem­per­a­ture is the same through­out. You will feel warmer if you po­si­tion your­self closer to the in­side of the house be­cause the cold ex­ter­nal walls are fur­ther away. So try and place your fur­ni­ture next to an in­ter­nal wall.

If your desk is up against an ex­ter­nal wall so you can look out of the win­dow your legs will tend to get cold, though you can re­duce this ef­fect by lean­ing a card­board sheet against the wall.

If the head of your bed is next to a cold ex­ter­nal wall you will be prone to get­ting a stiff neck, though you can counter this some­what by us­ing a solid head­board. The best so­lu­tion, of course, is a four-poster bed, but most bed­rooms just aren’t big enough.

So know­ing some­thing about how heat moves can help you brave the cold win­ter. My ex­pe­ri­ence has also shown that in­ves­ti­gat­ing the ther­mal prop­er­ties of your house with an in­frared cam­era will keep your kids amused for hours.

Run fans in re­verse Most peo­ple think of fans only when they want to be cool, but many ceil­ing units come with a handy switch that re­verses the di­rec­tion of the blades. Coun­ter­clock­wise ro­ta­tion pro­duces cool­ing breezes while switch­ing to clock­wise makes it warmer: air pooled near the ceil­ing is cir­cu­lated back into the liv­ing space — cut­ting your heat­ing costs as much as 10%!

— The Con­ver­sa­tion

Switch­ing your fan to clock­wise makes it warmer.

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