High Performing Buildings - Spring 2008 - (Page 32)

• Rely on stratiﬁcation of heat within the monitor itself to help reduce cooling loads. Do not place supply and return grilles in this area; instead, let the heat stratify. Minimize the depth of the ceiling cavity. The depth of the well is important. The deeper the well, the harder it is for light to reﬂect down into the space. Figure at left shows the theoretical decrease in efﬁciency resulting from deep wells. According to an IESNA workshop, a 7 ft deep, square sky well with 70% reﬂectance loses 50% effectiveness because of well depth. • Smith Middle School was constructed at $750,000 under budget. The Lighting Research Center at Rensselaer Polytechnic Institute analyzed the daylighting performance and found that electric lighting was reduced by 64% and 78 tons of cooling were saved. The facility is 128,000 ft2 and the area daylit is 63,000 ft2. I M PAC T O F C E I L I N G C AV I T Y Light lost when depth of ceiling cavity increases. North-Facing Roof Monitors North-facing monitors, although effective in providing natural light, typically require at least 25% more glazing than south-facing monitors to achieve the same annual daylighting contribution. Because of the additional glazing needed and the lack of passive heat beneﬁts in winter, they are not as cost-effective as south-facing monitors. In many spaces, bafﬂes can be eliminated when using north-facing roof monitors because direct beam • Use ﬁre-retardant and ultravioletresistant bafﬂes to diffuse light. Space white bafﬂes, hanging parallel to the glass, to block direct beams from entering the space. capture passive heating in the winter months. This helps to replace the heat usually provided by electric lights. • • Design the south-facing monitor to bottom of the light well, contrast is greatly lessened if there is a transition between the vertical and horizontal plane surfaces. A 45-degree angled plane is good, but a curved transition is better. Make sure the colors used within the monitor well are very light with high reﬂectance. If acoustical ceiling material is used, ensure that the total assembly’s reﬂectance and acoustical properties are high. Spring 2008 • Minimize contrast at the intersection of the well and ceiling. At the HIGH PERFORMING BUILDINGS 32 Lightshelves can shade lower view glass.

Table of Contents for the Digital Edition of High Performing Buildings - Spring 2008

High Performing Buildings - Spring 2008
Daikin AC (Americas)
Contents
Seattle City Hall
SEMCO
3M Energy & Advanced Materials
Price
Sofame Technologies Inc.
Sweetwater Creek Visitor Center
ASHRAE Certification
Greenheck
Daylighting Strategies That Maximize Benefits
Energy Conservatory, The
ASHRAE e-learning
Ecobuild America
CTG Energetics, Inc.
Cambridge City Hall Annex
Tate Access Floors, Inc
Air-Conditioning, Heating, & Refrigeration Institute
31 Tannery Project
Building Owners & Managers Institute
Indian Springs Discovery Center
International Facility Management Association
ASHRAE Healthcare
Fulton Companies, The
AAON, Inc.

High Performing Buildings - Spring 2008