Environmental Engineering Reference
In-Depth Information
TABLE 9.8
Minimum System Size for Which an Economiser Is Required
Cooling Capacity for Which an
Economiser Is Required
Climate Zones
1A, 1B, 2A
No economiser requirement
2B, 3A, 3B, 3C, 4A, 4B, 4C, 5A, 5B,
5C, 6A, 6B, 7, 8
≥33,000 Btu/h (9.7 kW)
a
Source:
EEECBC EGYPTIAN Energy Efficiency Code, HBRC, 2012.
a
Where economisers are required, the total capacity of all systems
without economisers shall not exceed 480,000 Btu/h (140 kW) per
building or 20% of the building's air economiser capacity, whichever
is greater.
TABLE 9.9
High-Limit Shutoff Control Options for Air Economiser
Climate Zones
Allowable Control Types
1A, 2A, 3A, 4A
Differential enthalpy
a
1B, 2B, 3B, 3C, 4B, 4C, 5A, 5B, 5C,
6A, 6B, 7, 8
Differential enthalpy or differential
drybulb
Source:
EEECBC EGYPTIAN Energy Efficiency Code, HBRC, 2012.
a
Differential enthalpy is that between the return air and the outside air.
Zone Controls
Exception (a) to Section 6.5.2.1 of ASHRAE/IESNA Standard 90.1 [5] shall be
replaced by the following: zones for which the volume of air that is reheated,
re-cooled or mixed is not greater than the larger of (i) the
design outdoor
airflow
rate
for the zone, or (ii) 15% of the zone design peak supply rate.
Fan System Power Limitation
Controls
Systems shall have fan power limitations 10% below limitations specified in
Section 5.4.1 of EEECBC.
Exhaust Air Energy Recovery
The system shall comply with the energy recovery requirements within the
threshold limits in Table 9.10. Where a single room or space is supplied by
multiple units, the aggregate supply cfm (L/s) of those units shall be used in
applying this requirement.
Energy recovery systems shall have a minimum of 60% recovery effective-
ness. Sixty percent recovery effectiveness shall mean a change in the enthalpy
of the
outdoor air
supply equal to the 60% of the difference between the
out-
door air
and return air enthalpies at design conditions. For equipment with
airside economisers, provision shall be made for all outdoor and exhaust air
to bypass the energy recovery device when not being used.
