[Greenbuilding] [BULK] Re: [BULK] passive solar homes - floors

[George J. Nesbitt]

Biggest common mistakes in solar:  

#1 Not applying whole building system thinking. "Paying too much attention to passive heating, and none to passive cooling." Lawrence Lile

#2 "Not enough attention paid to increasing levels of insulation and  
meticulous air-sealing." Rob Tom(20+ year old knowledge, a superinsulated air tight home with modest south glazing will out perform a more aggressive solar design)

#3 "More often than not, throwing in way too much equator-facing glass  
instead." Rob Tom (see #1 above)

#4 "omitting properly scaled overhangs or other permanent shading devices to  
prevent unwanted gains during the summer months." Rob Tom (South windows need to be shaded in the summer, or you get overheating. East and west windows are harder to shade with overhangs, they have to be very wide and deep. East and west glazing should be minimized). 

#5 Too much slopping glazing (skylights and glass roofs), too hard to shade.

#6 "Too much south glass compared to the amount of mass;" Lawrence Lile (or maybe too much mass, especially un or under insulated exterior mass walls and slabs, especially in heating climates).

#7 Making something too complicated, technical, and active.
"Using boxes of rocks, hollow concrete blocks, or anything else that
can't be cleaned, to store heat." Lawrence Lile

#8 Making something ugly

#9 "Using heat reflecting or Low-E glass on the South." Lawrence Lile (Actually an unshaded south window should probably have a SHGC of .40 or less, a summer shaded/winter full sun window should probably have a SHGC of .60 or greater. The low E coating will improve the comfort and the heat loss of the windows, to a greater extent than they will reduce heat gain. East and west windows should have a SHGC of .40 or less.