All About Daylighting




So we all know that windows can provide a great view, right? But, if they are placed in the right locations, they can also save you money on your utility bill, as well as keep you more comfortable and productive at home or at work. This type of window placement is called daylighting, and it takes a simple concept to a whole new level.

What is daylighting?

Simply put, daylighting is the practice of using natural light to illuminate building spaces. Daylighting combines different variables: everything from the type of window, to window placement, to interior design, to controlling how sun light comes in, all of which work together to maximize benefits from natural sunlight. Good daylighting creates beautiful, appropriately lit spaces while saving energy. Geographical location and climate, building architecture, use and orientation are big factors in designing a successfully daylit building. Such a building is always the result of a combination of art and science, engineering and architecture.



Different daylighting practices

Consider this: windows that face south are best in the US: they let in the most light during the winter months, but little direct sun during the summer, keeping the inside cooler. North facing windows are also good for daylighting: they let in even natural light with little glare and little summer heat. Windows that face east and west don’t work nearly as well for daylighting. They do provide lots of light during the morning and afternoon, but this often comes with lots of glare and excess heat during the summer months. The fact is clear glass windows actually let in too much light, far more than what’s needed for effective lighting.The sun provides 7,000 to 10,000 foot-candles of light, while indoor office spaces only require around 50 foot-candles.



All of this extra light causes glare and also creates the “cave effect”, where the back of the space appears dark compared to other surfaces. When this happens, people start closing blinds and turning on overhead lights to reduce the contrast in the room. In an energy efficient daylit office building, the windows team up with sky lights to provide the most light you need. Also, adding a light colored ceiling helps it reflect and enhance the day light so that it fills the room.



What about the overhead lights? Most of the time, you don’t need them. The electric lights in modern buildings produce a lot of heat, while properly directed natural lighting generates almost no heat at all. Properly designed daylighting screens out 99 percent of the sun’s heat while providing 50 foot-candles of light, which is more than enough for most tasks. Additionally, the decrease in internally generated heat enables designers to downsize the air conditioning system. As a result, reduced costs can help pay for more daylighting improvements.

To account for glare, you can place hoods outside and around the windows. The hoods also cut down on summer heat, keeping the home or office cooler and more comfortable. On the inside, louvers or tinting reduce glare and also direct light to reflective surfaces inside, allowing plenty of natural light to come into the work areas. One big help to daylighting is the window technologies available today. Windows are now way more energy efficient. They insulate while still letting in the light you want. There are also electro-chromic windows: they are special windows that change with the brightness of the sun light outside. As the sun tracks across the sky, the window darkens to keep excess heat out. It is like giant polarized sun glasses.

Benefits of daylighting

Daylighting has real immediate and long term benefits both for homeowners and businesses that choose to adopt this practice. The big financial benefit is that daylighting reduces lighting costs, reduces cooling costs (in almost all climates, almost year round), and in new construction it can be accomplished without increased construction costs. All of these savings are good for your bottom line, whether you are a home or business owner. Thinking long-term, on a larger environmental scale, by consuming less energy, daylit buildings reduce fossil fuel use and carbon dioxide emissions associated with global warming and climate change. Lastly, daylit buildings have proven psychological benefits for the people that live and work in them. Studies have shown that students perform better on tests, shoppers in daylit stores linger longer and buy more, office workers demonstrate increased alertness and productivity, as well as are absent less often.

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