week 9- Electrical Systems and Lighting

What stood out first was how much lighting affects the energy a building uses. The slides explained that lighting creates one of the biggest heat loads in an interior, and that the mistake designers make most often is over-lighting a space. The less lighting used, the less air conditioning is needed. We also followed electricity from the utility company through overhead or underground lines and transformers to the building, and learned about cable types, electrical symbols, and energy management devices. The second part of the unit moved into lamps, which are all about matching the light to the space.

We compared incandescent, halogen, fluorescent, HID, and LED lighting. Incandescent lamps are warm, dimmable, and inexpensive, but they give off more heat than light. Fluorescent lamps are energy efficient, but disposing of them puts mercury in landfills. HID lamps are used in parking garages, factories, and outdoor areas, and LEDs last a long time but still have concerns over color consistency. What I hadn’t thought about before is that no lamp is simply the best one. A choice that works in a factory could be the wrong choice for a home. Color was the topic that connected most to my own work. CCT is measured in Kelvin and compares white light to sunlight, where a higher number looks cooler and a lower number looks warmer. CRI rates how well a lamp renders color on a 100-point scale, based on a comparison of eight colors. Together these two numbers decide how finishes, wood, and fabrics actually look once they are installed.

We also saw that light can be reflected, refracted, transmitted, or diffused depending on the surface, and that people perceive public and private spaces differently depending on the lighting. The sustainability section tied everything together. We talked about lumens per watt, light trespass, and light pollution, and how Green Seal recommends specific lamps for different spaces. Sensors were the part I found most useful. Daylight sensors adjust electric light to keep lighting consistent, and vacancy sensors turn lights off in empty rooms, which can save 30 to 50% of the energy. It made me realize that a lighting plan can save energy for the whole life of a building without the user ever noticing. Seeing the design process laid out made the priorities clear. A designer identifies the spaces and tasks, verifies the foot-candles, selects the lamp and luminaire, and then does the lumen calculations. All of it is communicated to contractors through the reflected ceiling plan, which has to be coordinated with the furniture layout, ceiling details, and other building systems. Lighting decisions have to be made early, and the design has to work around them. For a designer, that means understanding lighting well enough to explain it to the client and the rest of the team.

Sketches coming soon.