Net ZEB Case Studies - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 416

Table 7.15 Daylight measurement in the north wing open office area on a
winter sunny day, Jan. 16, 2013

Time Workstation Illuminance (lux) (Measured at 0.84 m

Height from Ground)

South (3 m
from south
façade)

Center (9 m
from south
façade)

North (12 m
from south
façade)

Cubical office
(1.8 m from
north façade)

09:00 700 210 90 150

10:00
(shown in
Figure
7.50 )

810 230 100 170

11:00 950 260 110 200
12:00 980 330 130 150
13:00 790 310 130 150
14:00 590 220 90 120
Note: Desktop is 0.71 m in height; the partitions around desktops are 1.07 m high;
and, partitions between workstations are 1.37 m high. The office walls have a
height of 2.03 m.

7.4.2.4 Space Conditioning System
The space conditioning of the office area is provided through a hydronic
ceiling slab radiant conditioning system ( Figure 7.51 ) with significant
thermal mass (a TABS system - see Section 2.2.3). The hot/chilled water
is provided by the NREL campus district heating/cooling center, which has
a central woodchip boiler and high-efficiency chillers. As shown in Figure
7.51 , a displacement ventilation strategy was adopted, partially in order to
fully expose the ceiling to the office space below. A raised floor creates 0.3
m height of space for under-floor air distribution. The 100% fresh air is
supplied at a neutral temperature of about 19.5 °C. The upper surface of
the concrete slab is covered with 25 mm of batt insulation with foil faces
(RSI 0.5) to improve the effectiveness of delivering heating or cooling in
the slab downward to the office space. Acoustic panels are hung just below
the ceiling slab to improve the open space acoustic isolation. Normal weight
concrete 76 mm (3 in.) thick was poured on 50 mm (2 in.) steel decking