Daylighting & Sustainability
From the perspective of URGENCY, daylighting doesn’t hit the top of the scale for sustainability in buildings. Most folks in the building industry will tell you that that honor goes to the two-headed beast energy use/greenhouse gases that affect climate change…. But I don’t want to talk about those today.
|source: Stephen Covey, 7 Habits of Highly Effective People|
Why should we care about daylight or views?
|a building with a true connection to its site: |
Fallingwater (1934) by Frank Lloyd Wright.
Image courtesy of Carol M. Highsmith via Wikimedia
The most basic purpose of shelter is to protect from the elements, whether that is temperature, precipitation or rain. But once we’ve accomplished that, the very next step is to let some of that nature in. (And the more time we spend indoors, the more important this is).
- Buildings without proper ventilation are damp and stuffy and can contribute to illness.
- Buildings without sufficient daylight are dim, sad (SAD), and even morbid.
- Buildings without views to the outside interfere with sense of direction and do not provide a connection to the passage of time (seasons or even times of day). Ch'i can become pent up, without a visual release. It can even be difficult to feel secure inside a building that no sentry can see out of.
Have you seen Joe vs the Volcano (1990) with Tom Hanks? Sure makes you wanna get a "real" job, eh?
This is the opening scene, where he trudges in to work down to the deep dark basement of this awful building with no
natural light to speak of. Every time someone says they like fluorescent light I think of Joe's arrival to his office.
By the way, the opening zombie march is based on a similar scene in Fritz Lang's amazing silent sci-fi Metropolis (1927), but that was made before fluorescent lighting, so I don't have any excuse to include it. See the trailer HERE.
|sunlight in a traditional Japanese building|
Image courtesy of mrhayata via Flickr
- direct daylight/sunlight (a harsher light; also adds heat)
- indirect daylight (bounced off of other surfaces; best quality of light)
Daylight-ING is the practice of purposely manipulating daylight for good. It's a fairly complex discipline in its own right, but there are some very simple concepts that everyone can do without fancy modeling.
So how to we create better daylight and views?
Big windows. LOTS AND LOTS OF BIG WINDOWS?
No, not really. The answer is (dah duh DUM).....
THE FIVE BASIC PRINCIPLES OF DAYLIGHT:
|Keeping direct sunlight out of your home during the summer|
and letting it in during the winter can unburden your a/c &
heating systems, save money & reduce your carbon footprint
(I don't think these folks knew what that was).
Image courtesy of starmanseries via Flickr
Rule 2. Sunlight is hot.No, really! So you don’t want direct sunlight to invade your building during the summer, but you might not have your feelings hurt if it visits during the winter.
|Two illustrations of a building with lots of window and an overhang facing south.|
On the left, the summer sunlight does not get inside; on the right, the winter sun does.
To do your own drawings, you'll need to know the solar angles. It's a simple calculation, go HERE.
|As the sun moves east to west, it stays on the South side,|
a high angle in the summer, a low angle in the winter.
The good news is that during the hottest part of the year, the hottest parts of the day can be narrowed to midday and afternoon.
|Sunshine filtered by a trellis overhang on the South side|
Image courtesy of Lee Cannon via Flickr
- At midday, the sun is overhead, slightly south of straight-up (in the northern hemisphere). Awnings, overhangs, or porches on the south side of a building can take care of the majority of the heat.
- In the afternoon, the sun is more difficult to control, still slightly south but lower in the sky on the west side. Because the sun is lower, awnings & overhangs won’t help much, because he'll just peek underneath them and blind you anyway. Vertical shades and fins can help quite a lot on the West side, though!
The WINTER sun is much lower in the sky during midday, on the South side.
What about those overhangs, you ask? As long as they’re not TOO deep, winter sun can peek underneath them and stretch a warm hand in your South windows. Some people even put thermal mass just inside their south windows to absorb some of that warmth and re-radiate it into the space as the day wears on.
Rule 3. All daylight is not equal.Though the same sun shines on us all, the quality, intensity and location of sunlight changes with the seasons and the time of day in a single location. These vary even more with a location change (luckily, buildings usually only have one location to deal with). It is supercool to be in a space where these changes are evident. Has anyone been to the Phoenix Public Library (by Will Bruder) on the summer solstice? Pictures don't do it justice, so I won't even try. Check it out.
Controlling daylight on the south side is the easiest thing. Therefore, this is typically the best place to put most of your window area (i.e. more windows/ bigger windows).
|Easter sunrise service, Jacob's Well, Kansas City, Mo.|
Image courtesy of timsamoff via Flickr
The clerestory windows are obviously facing East and during
this sunrise service create significant brilliance & glare.
If the windows had been lower and behind the pastor, the
direct sunlight would be visually uncomfortable.
- light colors reflect more than dark
- smooth and/or glossy surfaces reflect light more directly; textured matte ones diffuse the light more gently
- a flat surface will redirect light in one primary direction; a curved surface can distribute an array of light all over.
For purposes of visibility and visual comfort, it's best to avoid stark contrasts (dark and light right next to each other). Indirect light, diffused light, well distributed light: these are the grails of daylighting professionals.
For some basic guidance on what engineers consider ideal lighting, read pages 3-5 of this "engineering sound bite."
Rule 4. Use multiple methods to control daylight.Daylight is great; direct beams of light in your eyeballs when you’re cooking supper or sitting at a computer not so great. Glare kinda sucks, too. We looked above at determining the basic methods for controlling daylight, largely on the South and West sides of a building. The North side (in the northern hemisphere, at least) doesn’t typically need daylight control, though depending on your specific location, you might also want vertical shades on the East.
|near and middle garden view|
Image courtesy of Ruth and Dave via Flickr
|Tiny View, Cité de Carcassonne, France|
Image courtesy of Vicburton via Flickr
Rule 5. All views are not equal.Large picture windows are great for expansive natural views (lakefront or mountain views, for example). Some views are so tight and precious that the best solution is not an enormous window, but a small beautifully framed one (similar to how a small prized painting might be framed).
In addition to scale there is also distance to consider. Some views are far (like a mountain range), some are near (like a garden) and some
are middling, (like a neighboring grove of trees, a cityscape, or the waterfront pictured on the right).
Most of us don’t have the wealth to have property with a massive view. But just about ten feet (sometimes even less) of space can be configured to provide a near view.
|Ocean View Hotel, view of the|
Rocky Harbour waterfront.
Image courtesy of toddwight1 via Flickr.
How would this view be different if it were one
big window with no vertical divisions?
If you followed the other principles above, you’ll end up with a “sun tempered” home (the very first step towards passive solar design), which means most of your window area and a big fat overhang on the South side. If you’re also interested in privacy, that makes the South side ideal for facing a BACK yard, but not for a side that faces an immediate neighbor or a public street.
Barring that option (because lots facing north end up being only about 25% of the market), consider having your south side open upon a private (walled) courtyard or garden.
That’s it for today. Try noticing the windows that frame how you see the outside world. Are they configured for controlled daylight and views? Is there anything you can do to improve them?
Next week I’ll post the daylight homework and answer a question (be sure to submit any new questions if you have them!)