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increase cooling loads but reduce heating loads, so a better perfor-
mance can be expected. The fact that summer electricity shortage
is a longmunicipal problemaddsmerits to application of reflective
coatings. Furthermore, it should be noted that, although air condi-
tioning is on in both Buildings A and C (and hence the two buildings
have very similar air temperatures), the application of reflective
coatings still influences indoor thermal comfort by changing the
temperature difference between interior surfaces and air temper-
ature.
4.3. Comparison of coating effects applied on different surface
materials
In order to investigate the possible influence of different surface
materials on coating performance, the four materials presented inTable 2 were painted with coatings A, B and C. Their reflectances
were measured with a spectrophotometer (wavelength range:
300–2100 nm). It was found that the coating reflectance is not
affected by the material. Every set of samples was then simul-
taneously exposed to same environmental conditions. Surfacetemperatures and heat fluxes were measured. Fig. 12 presents the
measured exterior surface temperatures, interior surface temper-
atures and heat fluxes in the concrete slab. Average measured
temperatures and heat fluxes for all four types of tested materials
are listed in Table 3. Comparing reductions in surface temperatures
and heat flux as function of reduction in absorbed solar radiation,
the experimental results showed that material thermal resistance
has a small effect on exterior surface temperatures; however, it
has a more profound impact on interior surface temperatures and
of course on heat flux.
5. Conclusion
This paper presents experimental results for the impact of
solar reflective coatings on building surface temperatures, indoor
environment, heat gains and electricity consumption under real
weather conditions in summer and winter. Three types of coat-
ingswere applied on identical buildings and their performancewas
compared with a set of three separate experiments: free-floating
case, conditioned spaces and different envelope materials.
For the non-conditioned case, the results indicate the significant
effect of the coatings on lowering building surface temperatures.
In the summer, an increase of surface reflectance from 32% to
61% resulted in average reduction of exterior surface temperature
reduction of 6 ◦C on the west wall, and in the winter a respective
reduction of 8.3 ◦C on the south wall. The maximum reduction in
exterior surface temperature of thewestwall reached 19.9 ◦C in the
summer. Reductions in interior surface temperatures showed sim-
ilar trends. The average reductions in indoor air temperature and
globe temperature at 1.5m above ground were in the order of 2 ◦C
during both seasons. Mean radiant temperatures were calculated
fromthemeasured surface temperatures and respective angle fac-
tors. For a standing person in the center of the room, the average
reductions reached 1.8 ◦C in both summer and winter.
For the conditioned case, the indoor air temperature was con-
trolled at 24 ◦C. A reduction of 2.62 kWh in electricity consumption
was measured during a representative summer day, while an
increase of 2.55 kWh was observed during a typical winter day.
Considering the recommended set points for cooling (26 ◦C) and
heating (18 ◦C) in Shanghai, the estimated net overall effect of
increasing envelope reflectance from 32% to 61% is negative.
Finally, four different envelope materials were painted with
three different coatings (reflectivities: 32%, 42% and 61%) andwere
exposed to the same environment conditions. Surface tempera-