PartL ROI: HVAC System Tab

The HVAC System Tab contains controls used to set the rooms, zones and HVAC systems for PartL ROI calculations.

Each zone has its own HVAC system and data for this HVAC system must be set up before a PartL check can be carried out. The data for defining the HVAC system is on the HVAC System Tab. All the included rooms in a zone are assumed to be served by the zone HVAC system. There is additional data related to rooms within the zone, which may vary between rooms. This data is on the Room data tab and enables such data as lighting and ventilation to be defined individually for rooms within the current zone.

Setting	Description
HVAC System	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.
Heating System	You need to 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, you 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.
Cooling System	If the HVAC system requires cooling, then you must 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 – When enabled shows if the HVAC system has mixed mode operation strategy.
System Adjustments	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
Heat Recovery, Controls and Metering	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. 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