Introduction 1 The use of skylights has grown in recent years both because they enliven building interiors and because they can save energy dollars through daylighting Skylighting can be a solid asset for buildings and satisfying for building designers occupants and owners Skylights can make a number of major contributions to the built environment since they Provide excellent lighting conditions to the interior of buildings Reduce the use of electric lighting to save energy and reduce peak electric loads when combined with photocontrols Satisfy human needs for contact with the outdoors Increase safety and security with highly reliable daytime lighting Provide emergency smoke vents We have prepared these Guidelines to help you use skylights to maximum advantage in commercial and industrial buildings They describe opportunities for energy savings and good lighting design offered by skylights They explain how to integrate skylights with the other building elements They show how to estimate the possible energy and dollar savings Finally they help you avoid mistakes that could reduce the value of your skylight design These Guidelines apply primarily to skylight applications designed to provide uniform lighting for commercial or industrial buildings They refer to manufactured off the shelf skylight components used in commercial applications commonly referred to as unit skylights These are typically simple rectangular or linear skylights although with creativity they can be applied to nearly any design situation Many of the lighting principles covered here are also applicable to residential buildings although the energy impacts are entirely different in homes and should not be extrapolated from the information in this handbook Similarly atrium skylights and other large custom designed skylights involve many other issues that are not addressed in this publication The reader is referred to more specialized texts and tools for the analysis of custom applications introduction 1 1 1 1 How Skylights Improve Buildings Skylights use the most ancient and universal light sources the sun and the sky to bring natural light into buildings This daylight can do many useful things for the building and its occupants At the most basic level daylight can illuminate the people and activities that occupy the building Depending on the design of the skylight system the daylight can be uniformly spread over a wide area or it can be localized for particular tasks For many types of buildings skylighting is a very practical complement to electric lighting Beyond basic illumination however daylight helps buildings to be more attractive for human occupation It brings some of the lively qualities of the outdoor environment indoors The movement of sun and clouds across the sky produces a more interesting environment than does constant interior lighting The differences in brightness and changes in lighting color evoke a pleasant response in people Skylights also can improve the appearance of architectural spaces and detailing A dramatic ever changing light source models form and helps people to perceive and enjoy shape color and texture Daylight also helps plants to grow which further enlivens the interior of a building For these reasons and more skylights are a desirable amenity that makes people feel good about their environment and improves morale As an additional benefit the amenities of skylights can raise the value of real estate through higher rents and resale prices When asked what the greatest advantages of skylights were a random survey of building professionals overwhelming responded natural light as the most important quality This was augmented by those who believed that skylights provided better light better working conditions better color or better aesthetics Altogether the people who named improvements to the lighting quality of the building as the most important characteristic of 1 skylights represented 82 percent of the sample Figure 1 1 Skylights Improve All of these advantages and benefits of skylights have their exceptions of course but with Buildings good design you can avoid problems Considerations for the designer to take into account when designing skylight systems for daylighting include 1 2 skylighting guidelines Visual and thermal comfort Seasonal and daily shifts in daylight availability Heat loss and heat gain Integration with the electric lighting system Choice of daylighting control strategy Integration with the roofing system Integration with the HVAC design Utility costs and peak electric demand Structural and safety concerns The following chapters will give you the information and tools you need to design good and valuable skylighting systems and will help you avoid problems With effective design everybody will be a winner your building its occupants and you too Clearly the primary role of skylights is to provide the best possible lighting conditions in the buildings they serve and to enhance the visual environment so that the occupants of the building can be as productive and comfortable as possible It is in this spirit that this Skylighting Guidelines book is written to help the designer and building owner understand how to apply skylights to their buildings for maximum effect How Skylights Save Energy 1 2 Skylights save energy by providing adequate daylight illumination in buildings so that electric lights can be turned off when they are not needed Daylight costs nothing and adds considerably less heat to a space than the equivalent amount of illumination from electric lights By reducing the amount of heat contributed to a building by electric lighting skylights can also significantly reduce the need for cooling Skylights can potentially also increase heating loads by allowing more heat to escape through the roof and increase cooling loads by letting more of the sun s heat enter a building The optimum balance of lighting and cooling savings versus increased needs for heating or cooling is a function of the building design the building operation and the local climatic conditions However the potential energy savings are substantial To give you a quick sense of the magnitude of these savings we calculated the potential savings for a few typical buildings 2 in the Los Angeles area using 1998 energy costs weather conditions from the San Bernardino Valley and many default assumptions An average grocery store might save about 16 000 per year in operating costs or 32 sf with the use of
View Full Document
Unlocking...