ASHRAE Journal - May 2014 - 20

Technical FeaTure

air velocity, CO2 and mean radiant temperature sensors. Using the European Standard
DIN EN 7730, the radiant side of the building
had a predicted percent dissatisfied rating
of 7.9% as compared to 8.7% for the VAV portion of the building. They did find that the
CO2 levels in the radiant side of the building were slightly higher than the VAV side of
the building. This has since been rectified
through a small increase of the amount of
outdoor air provided by the DOAS AHU.
Later, detailed monitoring of IAQ was
conducted by SGS India Pvt. Ltd. Its report
found that all comfort parameters were
within the limits of ASHRAE Standards
55-2004 and 62.1-2007.
The most important finding is based on
the survey of the building's occupants. The
University of California, Berkeley Center
for the Built Environment survey found
increases in occupant comfort. The group
that fell in the "satisfied or very satisfied"
category grew from 45% on the VAV portion of the building to 63% on the radiant
portion.

Mar. 27
108°F

110°F
100°F

Dec. 10
97°F

Jul. 2
93°F

Feb. 15
93°F

Sept. 15
93°F Oct. 28
88°F

90°F
80°F
Apr. 21
73°F

70°F

50°F

Nov. 17
52°F

Dec. 28
50°F
Dec. Jan.

Sept. 9
70°F

Jun. 25
70°F

60°F

Oct. 19
66°F

Mar. 4
57°F
Feb.

Mar.

Apr.

May

Jun.

Jul.

Aug.

Sep. Oct. Nov.

Figure 7: Dry-bulb profile, Hyderabad, India, November 2012 through October 2013. Source: Weatherspark.com

80°F

Nov. 27
72°F

70°F

Apr. 24
75°F

Aug. 17
77°F

Jun. 8
73°F

Jul. 13
64°F
Nov. 6
54°F

Oct. 3
75°F

Feb. 15
64°F

60°F
50°F

Cost

May 22
115°F

120°F

May 31
57°F

Aug. 24
63°F
Oct. 18

46°F
One of the most important elements of any
40°F
new technology is the capital cost. Higher
Apr. 17
30°F
capital cost usually means higher risk and,
34°F
Dec. 26
30°F
therefore, slow adoption. In the case of radiMar. 3
20°F
ant cooling in the SDB-1 project, the capital
23°F
Dec. Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov.
cost of the system was slightly lower than
the VAV system. A detailed breakdown of
the HVAC costs incurred for the building is
Figure 8: Dew-point profile, Hyderabad, India, November 2012 through October 2013. Source: Weatherspark.com
shown in Table 1 (Page 23).
This lower cost is a major factor in drivlighting. Chiseling into the ceiling and repairing the leak
ing the radiant cooling technology for
occurred quickly and easily.
future Infosys buildings. One of the main objectives
Condensation was not a problem in the buildthat Infosys set out to achieve through this building except for on the uninsulated manifolds. Once
ing was to test the cost implications of lower energy
identified as a problem, the manifolds were quickly
buildings.
insulated.
Lessons Learned
Turning the slab off one to two hours before unoccuThe contractor had two leaks in the radiant tubing over pied hours and back on one to two hours before occuthe whole 125,000 ft2 (11 613 m2) of the building when
pancy used less energy than running the slab at lower
an electrical contractor drilled into the ceiling to install
loads throughout the day.
20

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ASHRAE Journal - May 2014

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