Transcript Treatment of Mechanical Ventilation Heat Recovery Systems

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
MEV
MVNHR
MVHR
SFP
0.8 W/litre/sec
2.0 W/litre/sec
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
Outlet terminal
Fan unit
Kitchen
exhaust
Bathroom
exhaust
Toilet
exhaust
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
Duct from fan to
Supply terminal
T1
Duct from fan to
Outlet terminal
T4
Heat recovery
and fan unit
T3
Kitchen
exhaust
Bathroom
exhaust
Toilet
exhaust
T2
Bedroom 1
Bedroom 2
supply
supply
Lounge
supply
Kitchen/dinner
supply
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
Duct from fan to
Outlet terminal
Duct from fan to
Supply terminal
Fan unit
Kitchen
exhaust
Bathroom
exhaust
Toilet
exhaust
Bedroom 1
Bedroom 2
supply
supply
Lounge
supply
Kitchen/dinner
supply
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
Search SAP Appendix Q Database
www.sap-appendixq.org.uk
Search SAP Appendix Q Database
www.sap-appendixq.org.uk
Search SAP Appendix Q Database
www.sap-appendixq.org.uk
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
Example
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 [email protected]