May 2007

Energy Efficient Lighting in Harpeth Hall School's New Facilities

During the past six years, Harpeth Hall has built the Ann Scott Carell Library, the Patton Visual Arts Center, the Dugan Davis Track and Soccer Complex, the Daugh W. Smith Middle School, and the Hortense B. Ingram Upper School. In addition to meeting stringent energy codes, the design team has made every effort to select energy efficient light fixtures, as well as maximizing the use of natural daylight through large windows and skylights.

A majority of the interior lighting in these buildings uses fluorescent technology. Fluorescent lighting is so widely used because of its energy efficiency and extremely long lamp life. The technology has advanced greatly in recent years, providing warmer and more pleasing color rendition, higher efficiency, dimming opportunities, and better quality of light.

The fixtures used in the classrooms and corridors use T-5 and T-8 bulbs, which are more efficient, providing more light output per watt of energy used. The indirect / direct lighting used in the classrooms, corridors, and library reading rooms is easier on the eyes and works well in areas where computer and video screens are used, because the ceiling is used to reflect the light indirectly and more evenly.

While classrooms in the Upper School use dimming fixtures to lower light output, the Middle School utilizes 'dual switching' for the classroom lighting, which controls the multiple bulbs in the fixtures separately. The fixtures have 3 tubes: when both switches are on, all 3 are lit; when one switch is on, either 1 or 2 bulbs are on, providing low and medium light output.

Fluorescent bulbs come in many shapes and sizes, from simple linear tubes, to shorter, double tubes. Compact shapes include triple and quad tubes, and those that swirl similar to soft serve ice cream. The former are typically used in commercial recessed can lighting, while the latter are easily found at stores like Home Depot for residential use.