Choose whether your project is new construction or one of the three window
replacement types. The effect of excessive air infiltration through
existing operable windows is added to COMFEN-calculated energy
savings for each replacement window comparison base case. Click here
to review air infiltration calculation methodology and assumptions.
Choose to see performance information by performing a Rank or
Compare. "Rank" will order the performance results of a selected design
condition returning results on annual energy, peak demand, carbon
emissions, daylight, glare, condensation prediction or costs savings
compared to a generic double clear window (for new construction) or a generic single clear window (for replacement). "Compare" lets you choose four
design scenarios to compare the performance between those scenarios.
The assumptions for the simulations are based on a perimeter zone model.
Commercial buildings are divided into different thermal zones which can
be served by different HVAC and lighting systems. The different spaces
have different temperature and ventilation (outside air) requirements
and often different operating schedules. The focus on the individual perimeter zone then can be applied generally to whole-building and site
design. COMFEN, energy modeling software, was used to generate the results. COMFEN can help choose an
energy-efficient and cost-effective window for a given application. It
calculates heating and cooling energy use, peak heating and cooling
demand, and visual and thermal comfort for specific window products.
Updated information, future releases, and program information about
COMFEN and other software tools (such as WINDOW, THERM, and Optics) from
the Windows and Daylighting Group at LBNL can be found at