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tion occurs on the west wall (maximum 19.9 ◦C, average 6 ◦C),
with the south wall following. In winter, south wall has the great-
est exterior temperature reduction (maximum 17.2 ◦C, average
8.3 ◦C), with the west wall following. Interior surface temperature
reduction shows a similar trend. Detailedmeasurements of surface
temperatures for the west and south wall with two coatings are
presented in Fig. 6. It should be noticed that the difference between
exterior and interior surface temperature reduction indicates thedifference of surface heat gain. Therefore, awestwall in Shanghai is
the best location to use reflective coatings because it has the great-
est heat gain reduction in summer and less heat loss increase in
winter when compared to other orientations. Another factor that
has to be considered is thatwestwalls usually have smallerwindow
ratio than south walls.
Measured indoor air temperature and globe temperaturewithin
work area (at 1.5m from floor) are shown in Fig. 7. The results
indicate that application of reflective coatings reduces indoor air
temperature and globe temperature in both summer and winter.
The average reduction in air temperature is 1.8 ◦C in the summer
and 1.6 ◦C in winter; globe temperature was reduced by 2.3 ◦Cin
the summer and by 2.1 ◦C in winter respectively.
The mean radiant temperature is a key factor influencing occu-
pants’ thermal comfort; it can be calculated fromthemeasuredwall
surface temperatures (Eq. (1)).The average daily total solar radiation is 15.5MJ/m2 in summer and
10.9MJ/m2 in winter, while the average daily mean ambient tem-
perature is 28.6 ◦C in summer and 11.3 ◦C inwinter. Fig. 10 presents
themeasured average temperature differences of exterior and inte-
rior surfaces for each wall. Air conditioning operation results in
smaller temperature decrease.
Since the indoor air temperature are controlled at 24 ◦C in both
summer and winter, all walls have similar temperatures in Build-
ings A and C. Heat gains through walls depend on exterior surface
temperatures. As shown in Fig. 10, exterior temperature reduction
in summer is smaller than in winter, so it is reasonable to expect
a smaller heat gain reduction in summer than heat loss increase in
winter. The measured electricity consumption for air conditioning
also indicates such a trend (Fig. 11). Note that the average air tem-
perature ofworking hours in cooling period for Shanghai is 29.3 ◦C,
and the average daily total radiation is 18.2MJ/m2; respectively, the
average temperature of working hours in heating period is 10.4 ◦C,
and the average daily total radiation is 10.1MJ/m2.
The reduction in daily electricity consumption for September
is 2.62 kWh between Building A and C, while the increase in daily
electricity consumption for December is 2.55 kWh. Annual electric-
ity consumption changes can be estimated as follows: assuming
that the electricity consumption has a linear relationship with
indoor-outdoor temperature difference, and considering that the
recommended cooling and heating set points in Shanghai are 26 ◦C
and 18 ◦C respectively. The cooling degree hour within working
time is 2443.1 h and the heating degree hour within working time
is 11471.6 h in Shanghai. Then the total reduction of cooling elec-
tricity consumption is estimated to be 116.4 kWh and increase of
heating electricity consumption is equal to 327 kWh. In this esti-
mation, only envelope heat gain is considered, neglecting all other
heat gains, for example occupancy and equipment heat gainswhichFig. 11. Measured electricity consumption with air conditioning for representative
days in (a) September and (b) December with two different coatings.