Post on 16-Dec-2015
Treatment of Mechanical Extract Ventilation and Balanced Whole House Mechanical Ventilation
in DEAP
Date October-2007
Definition of Ventilation Systems Ref: DEAP Manual Section 2.6
Mechanical extract ventilation (MEV):is a fan driven ventilation system, which only extracts air from the dwelling. The DEAP calculation is based on a throughput of 0.5 air changes per hour through the mechanical system, plus infiltration.
Balanced whole house mechanical ventilation no heat recovery (MVNHR):is a fan driven ventilation system, which provides fresh air to the rooms in the dwelling and also extracts exhaust air from the dwelling. The system is not fitted with a heat recovery unit. The DEAP calculation in such cases is based on a throughput of 0.5 air changes per hour through the mechanical system, plus infiltration.
Balanced whole house mechanical ventilation with heat recovery (MVHR):
is a fan driven ventilation system, which provides fresh air to the rooms in the dwelling and also extracts exhaust air from the dwelling. The system is fitted with a heat recovery unit. The DEAP calculation in such cases is based on a throughput of 0.5 air changes per hour through the mechanical system, plus infiltration. The heat loss by mechanical ventilation is reduced by the factor v where v = 0.66 is the default efficiency assumed for the heat recovery system.
DEAP Default Data: Specific Fan Power
• The fans in mechanical ventilation system consume electricity.
• The electricity consumption is reflected by the specific fan power (SFP) of the unit.
• Default SFPs are detailed in DEAP Table 4g:
System Type SFP
MEV 0.8 W/litre/sec
MVNHR 2.0 W/litre/sec
MVHR 2.0 W/litre/sec
DEAP Default Data: Heat Exchanger Efficiency
• MVHR systems recover heat from the exhaust air and use this to warm inlet air.
• The efficiency of the heat recovery system is reflected in the rated heat exchanger efficiency of the unit.
• The default heat exchanger efficiency used in DEAP is 66%
• The DEAP software uses the default data unless otherwise specified
Treatment of Mechanical Ventilation Heat Recovery Systems in DEAP (default values)
Select appropriate ventilation system and default values are
automatically used
Treatment of Mechanical Ventilation Heat Recovery Systems in DEAP (default values)
Click here and you will see the default values
Testing Ventilation Systems• Test methods• Developed by EST (Energy Saving Trust), BRE (Building Research
Establishment), TEHVA (The Electric Heating and Ventilation Association), RVA (Residential Ventilation Association)
• Based on the European standards • Must be read alongside the European standards:
• BS EN 13141-6:2004 to define the duct configurations• BS EN 13141-7:2004 covering testing of heat recovery ventilation• MVHR Test temperatures
Operation of MEV Systems
Kitchen exhaust
Bathroom exhaust
Toilet exhaust
Outlet terminal
Fan unit
1. SFP (W/litre/sec) - power input to the fan at the minimum flow rate at each operating point when the system is installed in accordance with the manufacturers instructions.
Operation of MVHR Systems
Bedroom 1
supply Bedroom 2
supplyLounge supply
Kitchen/dinner supply
Kitchen exhaust
Bathroom exhaust
Toilet exhaust
Duct from fan to Outlet terminal
Duct from fan to Supply terminal
Heat recovery and fan unit
T1 T4
T3 T2
1. SFP (W/litre/sec) - power input to the fans at the minimum flow rate at each operating point when the system is installed in accordance with the manufacturers instructions.
2. Thermal performance (efficiency) of assembled supply and exhaust package with heat recovery used for a single dwelling (T2 - T1) / (T3 – T1)
Operation of MVNHR Systems
Bedroom 1
supply Bedroom 2
supplyLounge supply
Kitchen/dinner supply
Kitchen exhaust
Bathroom exhaust
Toilet exhaust
Duct from fan to Outlet terminal
Duct from fan to Supply terminal
Fan unit
1. SFP (W/litre/sec) - power input to the fans at the minimum flow rate at each operating point when the system is installed in accordance with the manufacturers instructions.
Procedure for Handling Ventilation Systems with more Efficient Parameter Data
1. Search the SAP Appendix Q Product Database (www.sap-appendixq.org.uk )
2. Use the product specification to identify the appropriate specific fan power or the SFP and Heat exchanger efficiency for the configuration that best matches that of the particular dwelling – including the nature of the ductwork, viz. rigid or flexible.
3. Enter the specific fan or the specific fan power and heat exchanger efficiency values directly in to DEAP software, Ventilation tab.
Example
Refer to the Specification for the Appropriate Product (example below)
Select the Specific Fan Power and Heat Exchanger Efficiency (if MVHR) for the
configuration that best fits the assessment dwelling
ExampleExample
Enter the Data into DEAP Software, Ventilation Tab
Energy saved by MVHR system should not also be entered into Energy Requirements, Fuel Data Tab
Other Considerations• Dwellings with MEV/MVHR systems will yield better
BERs when combined with improved air tightness measures.
• If a product is not listed on SAP Appendix Q, product manufacturers should refer to the “Testing Standards” page on SAP Appendix Q website for details of how to get a product listed.
DEAP Queries
• Refer to guidance in DEAP manual
• Check FAQ section of www.sei.ie/ber
• Email deap@sei.ie