Recent Posts

LBNL “Smart Ventilation” Research

Lawrence Berkeley National Lab (LBNL) scientists, led by Max Sherman and Iain Walker, are investigating whole-house ventilation options to support California's Zero Net Energy Homes initiative. This research project is called Smart Ventilation for Advanced California Homes (SVACH). California's energy-and-climate goal calls for all new residential buildings in California to be zero net energy (ZNE) by 2020.   Smart Ventilation and Airtightness To meet ZNE requirements, the building industry mustContinue Reading

Sliding Glass Doors: Comfort and Energy

Sliding glass door heat flow A sliding glass door’s large expanse of glass transmits a lot heat out of the home in the winter and into the home in summer. This heat flow takes three forms: heat conducts directly through the glass in winter, solar heat transmits through the glass in summer, and air that leaks around the edges of the door. Heat travels rapidly through glass when there isContinue Reading

Attic Vents and Venting – Part 2: Beyond the Simple Vented Attic

Attic vents and attic venting are the most familiar and reliable roof venting option. That was the subject of part 1 of this post. But they may not work depending on the building's design. Features like sloping ceilings and cathedrals may dictate an unvented attic. An unvented attic and insulated roof are also a good idea if the building's HVAC system and ducts are in the attic. This strategy keeps the mechanicalContinue Reading

Attic Vents and Venting – Part 1

Attic vents and roof venting serve a variety of purposes, depending on roof design and climate. These purposes include preventing ice damming, drying building materials, and controlling solar heat gain. In cold climates, we want to avoid ice damming by keeping the roof deck cold. In all climates, we want ventilation air moving against the roof deck to help keep our vulnerable roof deck dry. Roof ventilation also helps to prevent solarContinue Reading