Prospects for highly insulating window systems
Windows and other fenestration systems are often considered the weakest links in energy-efficient residences. This opinion is reinforced by building standards, audit guidelines, and standard window performance evaluation techniques geared toward sizing building HVAC equipment. In this paper we show that it should be possible to design highly insulating windows (U < 0.12 Btu/hr-ft/sup 2/-F) with high solar transmittances (SC > 0.6). If we then view annual window performance from the basic perspective of control of energy flows, we conclude that it should thus be possible to develop a new generation of ''super window'' that will outperform the best insulated wall or roof for any orientation even in a northern climate. We review several technical approaches that suggest how such a window system might be designed and built. These include multiglazed windows having one or more low-emittance coatings and gas-filled or evacuated cavities. Another approach uses a layer of transparent silica aerogel, a microporus material having a conductivity in air of about R7 per inch. We conclude by presenting data on annual energy performance in a cold climate for a range of ''super windows''. 8 refs., 6 figs.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5428879
- Report Number(s):
- LBL-19492; CONF-8505167-3; ON: DE85014544
- Resource Relation:
- Conference: Conference on conservation in buildings: northwest perspective, Butte, MT, USA, 20 May 1985; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
RESIDENTIAL BUILDINGS
WINDOWS
DESIGN
FEASIBILITY STUDIES
THERMAL INSULATION
COATINGS
CONVECTION
DOUBLE GLAZING
GLAZING
HEAT TRANSFER
RADIANT HEAT TRANSFER
SILICA GEL
SPACE HVAC SYSTEMS
THERMAL CONDUCTIVITY
ADSORBENTS
BUILDINGS
COVERINGS
ENERGY SYSTEMS
ENERGY TRANSFER
MASS TRANSFER
OPENINGS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
320101* - Energy Conservation
Consumption
& Utilization- Residential Buildings- (-1987)