Daylighting Through Building Weight Loss: Thin Your Way to Sustainability
Ever been in a building so big that you can’t see a window or what’s going on outside?
A lot of modern buildings are so big, fat, and wide that you can get lost in their bowels and, unfortunately, those depths can’t function without the help of electrical or mechanical systems. They’re on life support, so reliant that a venture into the interior spaces is impossible without power. We’ve been designing caves!
Long gone are the days when architects and master builders had to rely on natural ventilation and daylight to make their buildings inhabitable without a torch. There may be a light at the end of the cave, though. Recent sustainability efforts like LEED, among others, are seeking to reintroduce some of these design elements for one reason or another, but they’re always optional, and the guidelines lack teeth.
Until recently, it has been cheaper to pay for electricity and gas over time than to pay more up front for a building to use less energy. That’s going to change soon. President Obama’s plans to increase energy efficiency and reduce fossil fuel consumption over the next twenty years is very ambitious. At first glance, it almost seems impossible to get to zero percent net energy use by 2030. Some of those goals can be met with renewable energy sources, onsite or off, but the rest of the savings will need to be made up by simply cutting the energy we use. How? Can you look around your office and pick out what you can live without?
In the past, would-be building owners sought the best buildings to suit their needs for the least money. But are building designs and costs truly independent of sustainability and conservation factors? It usually costs more, however slightly, to build something that’s more environmentally responsible, whether for better-quality materials or for the design expertise to put it all together. So, what doesn’t show up as a cost of building instead takes on a long-term cost on people, resources, and the environment. Some of that deferred cost has already come back around, hence the sustainability movement.
Now, economically and geometrically, the cheapest typical building shape that best utilizes open space is one that looks like a pancake or cube. Any other shape and you could end up spending more on the skin, structure, and support systems. The core of thinner buildings takes up more of the floor plate per floor and ultimately, less space is available per dollar spent. Owners also like to maximize the building footprints on their land, oozing to the edges of the plot and thickening the building. So, the tendency and enticement to ‘fatten up’ a building persists.
Why, then, do we want thinner?
One problem with the fat design is that there is no opportunity for natural airflow. Interior walls and the sheer breadth of the floor plate are not conducive to promoting airflow from one outer wall to another. Mechanical ventilation is introduced without any further consideration, and it takes on the role of breathing for the building. Mechanical ventilation = energy use.
Daylight, too, is proportional to distance from windows (skylights are great but only for the top floor). Without daylight delivery integrated into the façade design, the effective daylight zone is about twelve to fifteen feet into a space. With lightshelves or other daylight redirection devices, you can potentially get up to thirty feet into the space. So generally, a building any wider than sixty feet can’t fully take advantage of natural lighting. No available daylight = electric light = energy use.
Building energy use varies by building type and location, but the four major energy sponges are heating, cooling, lighting, and plug loads. Let’s assume that we won’t be giving up refrigerators or computers anytime soon, so our plug loads are here to stay. That leaves the big three – heating, cooling, and lighting – which we have the least control over as occupants, and the most impact on as designers. By designing our buildings to passively take advantage of heat, light, and air from outside, we can rely less on the electricity-based systems we use to force life support into the centers of our caves.
Ask yourself: “Will my building be able to function if we run out of, or are not allowed to use, electricity or gas?” The answer should be yes!
Are there any other reasons for thinning up our buildings for natural ventilation and daylight? Three great ones: these energy sources are free, readily available, and are products of the environment instead of an impact against it. As lighting designers, we can confidently say that the most energy-efficient electric lighting is the kind that is turned off.
Photo Credits: Dagbrown (1); Global Jet (2); Mark Sebastian (3)
