10 Quick Tips Regarding Passive Solar Energy

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PHOTO: FOTOLIA/ELENATHEWISE
In terms of energy return, it's best to place solar panels on the west or east sides of homes.

A number of significant new developments and discoveries regarding passive solar energy were presented at the Passive Division of the American Solar Energy Society meeting in 1985.

1. Natural Convective Airflow

Natural convective airflow is a very effective, self-balancing means of heat transfer in passive solar buildings. A two degree to 12 degree Fahrenheit temperature difference between rooms can produce a heat transfer rate of 2,000 to 20,000 Btu/hr by means of airflow through natural architectural features. This transfer rate is essentially proportional to the square root of the temperature difference between rooms. Often, this natural distribution is more than enough to keep all spaces comfortable.

Convection seems to be driven by temperature stratification of air in the room with the heat source — a sunspace, for example — so fans that force air down from the ceiling to reduce stratification can actually reduce heat transfer to adjacent rooms. What’s more, fans used to force air from one room to another are often ineffective; in one house tested by Los Alamos researchers, the fanned heat transfer rate was actually lower than that produced by natural convection.

In most cases, doorways are adequate for convective airflow. Paired high and low vents in sunspaces are not necessarily more effective than doors; if the vents significantly reduce stratification, heat transfer may be cut. — From “Natural Convection Airflow and Heat Transport in Buildings: Experimental Results, ” by J.D. Balcomb and G.F Jones of Los Alamos National Laboratory (LANL).

  • Published on Jan 1, 1986
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