Intelligent Design: Painting with the colors of the wind (or air flow anyway)

Let's talk about circulatin' the air, shall we?

There are basically two schools of thought. One is that mechanical systems - fans, heating, air conditioning - are capable of controlling the temperature inside a building, and that's the end of that. The other is that the design of the building itself can moderate its own temperature at a comfortable level, if it's designed to emphasize that.

It's pretty clear straight off what we tend to use in this day and age. For a long time, mechanical systems have been so cheap and are so much simpler that they've been the pick of choice.

But they take energy, and use it inefficiently. Lots of heating and cooling vents - especially in commercial buildings - are put way up high, for example, leading to most of the heat collecting pretty uselessly at the top of the room (easy to notice the next time you have to change a light bulb up high). Another source of inefficiency is air leaking or heat radiating through windows.

And that's starting to change a little - any list of environmental human improvements will include an array of insulation tips, and people are starting to get concerned about modern HVAC systems. But there's not much a house that isn't designed for natural heating and cooling can do in terms of being retrofitted - on the whole, it's going to rely on mechanical HVAC to maintain a comfortable level. Renovations can improve the efficiency of those systems, but not much more.

The simple truth is that maintaining a naturally-comfortable evel is a design challenge, and one that needs to be considered and embraced from the early stages of architectural design. There are a ton of factors to consider - temperature, shade, rain and snow, direction of the sunlight based on season, size of rooms. Just a whole lot of stuff!

But if it's done right, efficiency shoots through the roof. And a lot of new innovations are helping with it.

First, better insulation and sunlight-management/ in general, especially around windows. All sorts of double-glazed, triple walled windows are coming onto the scene that are very good at not only keeping a good amount of heat in but also keeping too much heat (in the form of sunlight) out. The physical structure of the building can help with this too - a slightly angled roof can let in sunlight during the morning and evening but keep it out during the hotter midday. And the layout of a room can have sunlight falling on an intermediate brick or tile wall which absorbs lots of heat during the day and radiates it a little slower in the evening.

Second, unpowered air circulation systems have hit the scene in a big way, spurred on by LEED certification (I'm getting around to LEED, I swear!). The idea here is that the physical fact that hotter air rises can be used to power a circulatory system. Essentially, vents at the top of a room collect warm air and funnel it into a pipe. The pressure of more warm air behind it pushes air through the pipes (imagine a line of parents on Christmas Eve waiting in line to buy a Wii, only with particles of warm air) which take it back down to vents in the bottom of the room. Suddenly, the only-slightly-cooler air is doing double duty in warming the house again. I'm a little more unclear on this, but in (my own) theory, the system should be able to work in reverse with cool air.

The key is that the air doesn't settle at the bottom or top of the room, which has two effects. First, it means that energy in the system - heat from sunlight - is used more efficiently, since it's in constant circulation. That leads to the entire room reaching an equilibrium temperature (designed to be a comfortable room temperature, which is part of the challenge) quicker and more efficiently, rather than the air in the room stratifying into regions of cold, room temp, and hot.

Second, the fact that air is in continual motion feels good, and can help cool you off. Really, the feeling of cooling is produced better through moving air than cold air, so an unpowered method of keeping the air in motion is helpful, especially if it's not windy outside and you can't get a cross-breeze going.

There's a lot more; designing a building that uses sunlight and ventilation efficiently is both challenging and entirely dependent on the building and site themselves. But still, there are ways of doing it - our pre-industrial ancestors have been doing it for a long time. Southwest Native Americans didn't live in caves because they couldn't build real buildings (far from it), they used caves because the stone and shade kept them at a comfortable temperature (and for defensive purposes, but that's an added bonus). In general, people's permanent dwellings were built with methods and materials that made them comfortable without the use of electricity (because it didn't, like, exist).

That said, to date, it has been cheaper to throw together a building and HVAC the hell out of it later. But consider this: 90% of the cost of a building (including construction, overhead, various utilities, and possibly renovations) after 10 years is in running it, not building it (I'll find a source for this when I have internet). So doesn't it make sense build 'em to run as efficiently as possible?

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