HVAC System
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An HVAC system type must be selected from the list.
All the included rooms within the currently selected zone are assumed to be
served by the system type. The
HVAC System Type shows a list of standard
HVAC system types. Selecting one of these HVAC systems will automatically set
up the appropriate HVAC data.
The
Include Zone check includes the selected
zone and enables several controls in Heating System and in System Adjustments.
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Heating System
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Specify the Heating system heat source, which
defines how heating is supplied to the HVAC system. In addition, the fuel type
is selected for the heating system. The remaining data items are used to
determine the efficiency of the heat generator (boiler). The required data is:
- Seasonal
efficiency – If the efficiency is known, this should be entered
directly, if not, the remaining data items are used to infer the efficiency.
- Generator
radiant efficiency – If the efficiency is known, this should be
entered directly, if not, the remaining data items are used to infer the
efficiency. If the HVAC system is a Radiant heater, then you can specify a
Generator radiant efficiency if it is known, if not, the efficiency will be
assumed based on whether the heating is on the Enhanced Capital Allowance (ECA)
list.
- Boiler on
ECA list – Defines whether the boiler is on the Enhanced Capital
Allowance (ECA) list. If not, define whether the boiler was installed after
1998.
- Installed
on or after 1998 - For boiler systems installed from 1998 onwards,
a default seasonal efficiency of 0.81 is suggested by the tool (based on
Statutory Instrument 1994 No. 3083), and for boiler systems installed before
this period, a conservative default seasonal efficiency of 0.65 is suggested.
Please note that from around 1989, the boiler industry began producing boilers
with efficiencies that would have complied with the above statutory instrument.
- System
uses CHP – This enables CHP generator data to be defined for the
zone on the
General tab.
The
Bi-Valent systems section allows a bivalent
heating system to be setup. This is when the heating is supplied by two or more
different types of heat sources.
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Cooling System
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If the HVAC system requires cooling, then specify a
Cooling system packaged chiller type and
the
Chiller rating.
If the chiller seasonal efficiencies
(Seasonal EER and
Nominal EER) are known, they should be
entered, if not, the efficiencies will be assumed based on whether the chiller
is on the Enhanced Capital Allowance (ECA) list.
Mixed mode operation
strategy – Enable to know if the HVAC system has mixed mode
operation strategy.
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System Adjustments
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The following system adjustments can be applied.
- Ductwork
has been leakage tested – If the system has been leakage tested,
the CEN classification (e.g. Class A) can be selected.
- AHU meets
CEN leakage standards – If the AHU meets CEN leakage standards, the
relevant standard (e.g. L1, L2) can be selected.
- Specific
fan power is known – If the specific fan power (SFP) is known, it
can be defined, otherwise a default value will be used.
- Auxiliary
energy of fanned warm air heaters is known – If the HVAC system is
a Flued/Non-flued forced convection air heater and the auxiliary energy of
fanned warm air heaters is known, it can be defined, otherwise a default will
be used.
Variable speed pump – If
specified HVAC system is one where variable speed pumping can be used these
options become available.
- Type of pump
- Type of variable
speed control
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Heat Recovery, Controls and Metering
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Zone based heat recovery –
Heat recovery for the HVAC system can be set up. Depending on the type of HVAC
system heat recovery is either specified at the zone level or the room level.
- Heat
recovery – Depending on the HVAC system specified, heat recovery
can be defined by selecting the type of heat recovery.
- Seasonal
efficiency – If a heat recovery system is selected and the seasonal
efficiency is known, it can be defined, otherwise a default value will be used.
Metering provision – The
effect of system controls can be considered as follows. These are not available
if Type of analysis is set to Scottish Building Regulations.
- HVAC
systems separately sub-metered – Metering should be included if
there is energy metering of plant and/or metering of plant hours run and/or
monitoring of internal room temperatures.
- Metering
warns of "out of range" values – Specify whether the metering warns
of out of range values.
Heating system controls –
Various heating system controls are available if Type of analysis is set to an
EPC calculation. These will trigger certain recommendations from being omitted
from the recommendations report automatically. The following options can be
selected:
- Central time
control
- Optimum start/stop
control
- Local time control
(ie., room by room)
- Local temperature
control (ie., room by room)
- Weather
compensation control
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