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Aug 032014
The sun rises higher in the sky in summer, and travels around more of it, than in winter.

The sun rises higher in the sky in summer, and travels around more of it, than in winter.

Many of the preferred locations for prepper retreats are in areas that have substantial swings in temperatures between hot summers (daytime temperatures often in the 90s and sometimes exceeding 100) and cold winters (where temperatures seldom rise above freezing, even in the middle of the day).

That’s no big deal when you have unlimited utility power for heating and cooling, limited only by your ability to pay the electricity or gas bill each month.  But in a Level 2 or 3 situation, there won’t be any utility power, and creating our own electricity will be expensive and always in short supply.

We need to make our retreat structures as energy efficient as possible so as to minimize the need for heating and cooling.

There are lots of ways to improve the energy efficiency of our retreats, and most of these are totally ignored in ‘normal’ building design and construction because it makes little financial sense to, for example, spend an extra $50,000 when building your retreat, and to get a $500 a year saving in energy consumption as a result.  But in a Level 2/3 situation, the cost of the energy might rise from $500 to $5000 or more, and/or it might simply not be available at any cost, and so the financial equation changes drastically, making it more prudent for us to invest up front in additional energy-saving techniques in order to enjoy the benefits if/when we need to rely on our retreat and make do with less energy.

The good news is that not all these strategies need to be expensive or inconvenient, and some of them actually add to the livability of your retreat.  One such example is adding what in various forms can be considered either an awning, a brise soleil, a shade or a veranda (verandah – both spellings seem acceptable) to your retreat’s southerly (and much lesserly, east and west-facing) aspect.  (We’re not explaining what an awning, shade or veranda is because you probably know, but the term brise soleil might be less familiar.)

The clever aspect of such structures is that they interact with and take advantage of the way the sun rises in the sky.  In the summer, the sun quickly climbs up to a near vertical position before descending again at the end of the day.  In the winter, the sun slowly staggers part-way up the sky before sinking down again.  This difference is also more exaggerated, the further you move from the equator, and most of us are planning our retreats to be far from the equator.


Note – as shown above – the sun rises a bit north of east and sets a bit north of west in the summer, but in the winter it rises south of east and sets south of west.

It covers more of the sky in summer, and you might notice appreciable sun coming in from west and east facing windows, and possibly even a little bit in northern windows too.  But it is the southern facing windows that most need the sun shading.


What this means – and as illustrated above – is that some sort of shading/blocking structure that prevents the sun’s rays from shining onto and into our retreat while the sun is high in the sky will reduce solar heating during the summer – the time of year when we most want to keep the sun off our retreat and out of our windows.  But during the winter, when we’re keen to get all the sunlight and warmth we can, the overhead structure won’t interfere with the sun’s rays at all.  Heads we win, tails we don’t lose!

Because these devices take advantage of the varying seasonal location of the sun, they can be fixed in position, making them potentially robust and low maintenance.

How much sun angle should they block?  One approach is to see the maximum angle in the sky for the sun in mid-winter, the angle at the equinoxes, and block off all angles greater than the equinoxes.  You can get this information from this helpful website – simply put in your location and then choose 21 December as the date, and that tells you the maximum height the sun reaches at your location in the winter.

For example, in Kalispell MT (48º12′ north) the sun struggles to reach 18.4º up into the sky.  Compare that to the summer solstice (21 June) when it reaches 65.2º.  At the equinoxes (21 March and September) the sun goes up to 42.2º – a number which unsurprisingly is sort of halfway between the two other numbers.

One other interesting thing is to note that the sun has risen to 42.2º in mid summer by 10.10am and doesn’t fall below it again until 5.10pm.

So perhaps it makes sense to accept something around the 42.2º point as the transition from when we want to allow sun into the house and when we want to block it.  That gives us full sun for half the year, and successively blocks off more of the sun during the summer season.

This calculation should be modified by an appreciation of what type of heating/cooling needs you’ll have at the equinoxes.  Will you still be wanting to heat the retreat, or will you be starting to need to cool it?  That will also influence how much shade cover you want above your windows.


Having some type of permanent shade over your southerly facing windows is a simple way of ‘automatically’ regulating and cutting down on the sun’s heat that transfers inside your retreat during the summer while not reducing it during the winter.

It is probably the most cost-effective thing to do in terms of improving your retreat’s energy efficiency and reducing its need for cooling during the summer.  Be sure to include shading if designing a new retreat, and be sure to add it if purchasing an existing dwelling structure.


David Spero[suffusion-the-author display='description']

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