This section outlines the methodology for the inclusion of centralised ducted whole-house heat recovery ventilation systems and mechanical extract ventilation systems.
Table 3.1 summarises the DEAP data entries for centralised mechanical ventilation systems. This is in addition to the make and model, to be sourced from the onsite survey for Existing and New Final, and from plans/specs for New Provisional BERs. Documentary evidence such as photos, plans, PDF documents, for the required data should be uploaded to DEAP.
Table 3.9 - Data entries for centralised mechanical ventilation systems
| Type | Data | Defaulta) | Source for non-default |
|---|---|---|---|
| Balanced whole house mechanical ventilation with heat recovery | SFP [W/(l/s)] | 2 W/(L/s) |
PCDB b) c) or equivalent testing. |
| Heat exchanger efficiency [%] | 66% | ||
| Balanced whole house mechanical ventilation without heat recovery | SFP [W/(l/s)] | 2 W/(L/s) | |
| Whole house extract ventilation | SFP [W/(l/s)] | 0.8 W/(L/s) | |
| Positive input ventilation (from outside) | SFP [W/(l/s)] | 0.8 W/(L/s) | |
| Exhaust air heat pump | SFP [W/(l/s)] | 0.26 W/(L/s) | |
| Exhaust air flow rate [m3/h] | Total dwelling volume/hr | Ecodesign data | |
| Positive input ventilation (from loft) | None | N/A |
Notes:
a) See also Table 3.7 for SFP.
b) SAP 2012 data from PCDB should be used if available, otherwise 2009 data.
c) The data from PCDB should be taken for the correct number of wet rooms. Non-default data may be used, subject to conditions for acceptance of test data. Acceptable data are those listed on the UK Product Characteristics Database (PCDB), formerly known as SAP Appendix Q.
The testing methodology for inclusion of mechanical ventilation devices on the PCDB invokes BS EN 13141-6 (definition of duct configurations) and BS EN 13141-7 (testing of heat recovery devices) and therefore is an approved and suitable method for Irish use. The methodology determines the unit performance (both in terms of SFP and heat recovery efficiency) for a number of predefined configurations, specifically the number of wet areas in the dwelling where humid air is extracted. The PCDB testing method uses extract flow rates that meet the TGD F requirements for minimum extract rates.
BER assessors should detail the ducting type and general configuration of the ventilation system when a non-default value is entered for SFP and/or ventilation system efficiency. The configuration should include the number of rooms where the ventilation system is extracting air (for example kitchen plus three wet rooms). The type of ducting may be flexible ducting, rigid ducting, or both.
Semi-rigid duct systems included in the PCDB have demonstrated that their aerodynamic performance, when installed in a variety of configurations, is at least that for rigid ducts. Where these duct systems are used with balanced mechanical ventilation, they are considered as equivalent to rigid ducting for the purpose of DEAP assessments. Otherwise, where the duct type referenced on PCDB performance data for balanced mechanical ventilation systems does not match the duct type installed in the dwelling, then default values must be used in DEAP for the balanced mechanical ventilation system. Semi-rigid duct systems in mechanical extract systems may not be considered equivalent to rigid ducting for the purpose of DEAP assessments even if listed in the PCDB, unless the unit specifies “semi-rigid” layout or duct type.
As detailed in TGD F, a wet room is a room used for domestic activities such as cooking, clothes washing, bathing, which, by their nature, are likely to give rise to significant production of water vapour. Typical wet rooms in dwellings are kitchens, utility rooms, bathrooms and sanitary facilities containing provision for showering or bathing.
For balanced whole-house mechanical ventilation systems with heat recovery, the assessor selects whether system ductwork outside the dwelling envelope is uninsulated:
In cases where external ductwork has not met the condition (in other words is uninsulated), DEAP multiplies the heat recovery system exchanger efficiency by a factor of 0.85.
If two or more systems are used in the same dwelling: