What is the difference between “passive” and “active” solar heating?
Passive solar heating refers to architectural design features in the home that capture the sun’s heat during daylight hours (and hopefully retaining this heat through the nighttime hours). Passive design features include: energy efficient south facing windows, thermal mass (masonry floors/walls/etc), well designed eaves on the house that allow sun in the winter but block it in the summer, home orientation on the property (to capture sun, and avoid cold winter winds), tree and shrub placement, etc. Passive solar design is the “low hanging fruit” of solar heating, and should be the first consideration in any heating system design. Active solar heating systems utilize collector panels and circulating pumps to “actively” collect and store the sun’s heat, and then move it around the home for use when/where needed. Active systems augment heat provided by passive systems, and can boost total solar heat generation to satisfy as much as 95% of heat load in the case of some well designed homes!
