High Performance Windows

Thermal and optical performance of residential and commercial windows

High Performance Windows

Strengthening a Building's "Skin"

Reflections in building facade
Office Building Facade

Building envelopes play a crucial role in the energy balance of buildings, imposing an annual 15.5 quad (quadrillion Btus) primary energy expenditure today (at a cost of $155 Billion) and a further penalty on peak space conditioning loads that must be offset by expensive HVAC systems and on peak electric loads that place a strain on the electric grid.

The long term transformative vision of this program aims to convert the overall building envelope (transparent and opaque elements) from today's net energy cost of 15.5 quads to ultimately become a net energy supply to the building. This is accomplished by:

  • Dynamically managing thermal flows daily and seasonally, via optical properties, conductivity and thermal storage
  • Utilizing and controlling daylight to offset electric lighting
  • Generating and/or storing electrical and thermal energy, respectively, in building envelope elements
  • Reducing uncontrolled air leakage through the building envelope and by employing innovative envelope elements to capture and manage air exchange, thus offsetting mechanical ventilation

Just as human skin is an all-important barrier and thermal regulator of the human body, the building "skin", as envisioned here, is the first critical element in defining goals for building energy performance and comfort.

The most efficient HVAC or lighting system is the one that does not have to work at all because the envelope has neutralized or captured the thermal load at the building skin and provided required interior illumination. These high-performance energy functions can be implemented while also providing view, security, thermal comfort, privacy, and aesthetic solutions demanded of building owners, thereby enhancing the economic attractiveness of these solutions and accelerating widespread market adoption. Windows though are often the lowest thermally performing component of the building envelope.

Berkeley Lab's Windows and Envelope Materials Group program is intended to address the highest priority elements of the vision outlined above. It addresses the most pressing technical and market barriers that impede achievement of this stretch vision for the building envelope.