Vermont Sun Structures: Solar Greenhouse Design and Construction
Vermont Sun Structures: Solar Greenhouse Design and Construction  
Vermont Sun Structures: Sunroom Design and Construction Glass

The technology of insulating glass and glazing materials continues to evolve. The energy efficiency of the new ‘LowE’ and ‘Heat Mirror’ glazings enable our sunrooms to deliver year’round comfort. To select glass for a project, it is necessary to understand the properties various glass combinations offer. Two basic objectives of the glass selection include:

1. High resistance to heat loss in winter.

The R-Value measures the insulating value of glass. Insulated glass uses 2 or more panes of glass with an air space between. Argon or Krypton gas is sometimes used to enhance the insulating value of the air space. Low E, or Low Emissivity glass is made with heat reflective layers to reduce the heat radiated from the glass.

2. Rejecting heat in summer.
Heat absorbing (tinted), and spectrally selective (admits visible light but filters out infrared heat) glass is used for overhead glazing and west orientations. The solar heat gain factor (SHGF) is the portion of available sunlight that is admitted through the glass as heat – very important for passive solar heating. Visible Light Transmission) (VT) is important for plant growth and daylighting.

National Fenestration Rating Council, NFRC