
570 Principles of Sustainable Energy Systems
© 2008 Taylor & Francis Group, LLC
cooling or heating season (f
C
, f
H
) and the seasonal coefcient of performance (COP) of the
cooling or heating equipment. Thus, Equation 9.40 can be expressed as
ES ES
COP
COP
ES ES
COPCOP
TL
CL
C
HL
H
TL
C
C
H
H
=+ −
=+−
1
(9.41)
It should be noted that the increased solar gain due to daylighting has not been included
here but would reduce summer savings and increase winter savings. If it is assumed that
the increased wintertime daylighting solar gain approximately offsets the reduced light-
ing heat gain, then the last term in Equation 9.41 becomes negligible.
To determ ...