We have put together a simple guide for compliance with TGD Part F 2019 (ROI) for architects, engineers, contractors - What are the ventilation options to achieve compliance: MVHR, MEV, DCV, etc.

1. BROOKVENT, 38-39 Fitzwilliam Square, Dublin 2, D02 NX53, Ireland
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What is Compliance?
TGD Part F – Main Points & 2019 Updates
 Mechanical Ventilation must be installed in buildings with an airtightness level <3 m³/h.m²
 Ventilation units much have min. 25% capacity above the general ventilation rate
 General ventilation rate of 0.3 l/s/m² or 5 l/s + 4 l/s/person
 All mechanical ventilation systems must have a status indicator to show system is
running/faults have occurred
 Systems to be designed and installed by a ‘competent person’
 All systems to be verified by a ‘Ventilation Validator’ to show TGD Part F compliance
Competent Persons
Any person designing or installing mechanical ventilation systems should be able to demonstrate
that they can be considered a ‘competent person’.
The only certified way to demonstrate competence is by obtaining a City and Guilds Ventilation
Certification. This can be obtained from a number of ETB centres nationwide.
There are other alternative methods to show competence but the above is the most straight forward
method.
Any designer or installer should be able to provide proof of competence to ensure compliance is
achieved.
Airflow measurements should be performed using a calibrated airflow device with an appropriate
hood attachment.
Validation
One of the main changes in TDG F 2019 is the introduction of the Ventilation Validation Scheme.
As part of this scheme all residential buildings with mechanical ventilation systems are to be tested
to ensure compliance with the regulations has been achieved.
The role of the ventilation validator is as follows,
1. Ensure airflow rates have been calculated correctly, in line with TGD F 2019
2. Test the actual airflow rates in all properties to ensure they match the designed airflow rates
TGD Part F Ventilation 2019 | Mechanical Ventilation Compliance Guide

2. BROOKVENT, 38-39 Fitzwilliam Square, Dublin 2, D02 NX53, Ireland
T 01 546 1004 W brookvent.ie E hello@brookvent.ie
Methods of Achieving Compliance – Mechanical Ventilation
With the introduction of NZEB standards and the upgrades to both Part F and Part L of the building
regulations there has been a move to discourage the use of natural ventilation as a means of
ventilation. Unless buildings have an airtightness of between 3 m³/h.m² and 5 m³/h.m² natural
ventilation cannot be used. The size and number of the openings required to achieve compliance has
let to natural ventilation not being an attractive solution.
There are 2 mechanical ventilation methods detailed in TDG Part F that are recommended to
achieve compliance: cMEV and MVHR.
Compliance can be achieved using other mechanical ventilation methods, but they will have to be
accompanied by an Agrement Cert to show that it is an appropriate solution.
cMEV - Centralized Continuous Mechanical Extract Ventilation
This is the most basic and cost-effective method of achieving compliance in buildings with
airtightness levels <3 m³/h.m² using mechanical ventilation systems.
A cMEV System must consist of the following to ensure compliance with regulations,
 A centralised extract fan (cMEV unit)
o The unit must be sized appropriately to the building with a minimum of 25%
capacity above the General ventilation rate
o The unit must be listed on the PCDB database for use with DEAP to avoid having to
use default values which may impact the BER rating
 Ducting to all wet rooms (Kitchen, Utility, Bathrooms, Sanitary Rooms)
o Ducting to be sized appropriately to designed airflow and distances
o Ducting can be rigid/semi rigid – flexible duct is not compliant
 Ducting to the outside to exhaust stale air from the building
o Insulated as appropriate
 Boost switch (where applicable based on calculations)
 External opening in habitable rooms of min. 2500mm2 equivalent area for provision of fresh
air to the building
o Typically, in the form of a 100/125mm standard wall vent (hit/miss type)
 Control indicators must show occupier the unit is running or if a fault has occurred
o Control indicators must be in a visible location and not above the ceiling
 Extract rates to be designed as per the formulae in TGD Part F and the unit to be
commissioned to these rates, both by a competent person.
 O&M Manuals must be available to the occupant so that the system can be operated and
maintained correctly.
BENEFITS – Fully Part F compliant, very cost effective, fast installation, no additional Agrement
certs necessary, commissioned using standard airflow devices.

3. BROOKVENT, 38-39 Fitzwilliam Square, Dublin 2, D02 NX53, Ireland
T 01 546 1004 W brookvent.ie E hello@brookvent.ie
MVHR/HRV – Centralized Mechanical Ventilation with Heat Recovery
This is the most energy efficient method of achieving compliance in buildings with an airtightness of
<3 m³/h.m² using mechanical ventilation. This system extracts stale air from wet rooms and uses the
energy in this air to warm up incoming fresh air which is being supplied to habitable rooms.
MVHR systems provide constant fresh, filtered, and warmed up air to a property. This system can be
more applicable in buildings looking to achieve top quality energy ratings as well as locations where
air quality and/or external noise may be an issue, e.g. adjacent to a busy road.
A MVHR/HRV System must consist of the following to ensure compliance with regulations,
 A centralised MVHR unit with both an extract and supply fan and a heat exchanger
o The unit must be sized appropriately to the building with a minimum of 25%
capacity above the General ventilation rate
o The unit must be listed on the PCDB database for use with DEAP to avoid having to
use default values which may impact the BER rating
o The unit should be located within the thermal envelope where possible to allow for
easy access for the occupant for maintenance
o Where there is a risk of overheating, it is recommended that the system allows for a
bypass of the heat recovery function
 Ducting to all wet rooms (Kitchen, Utility, Bathrooms, Sanitary Rooms) and habitable rooms
(Living room, dining room, bedrooms, etc)
o Ducting to be sized appropriately to designed airflow and distances
o Ducting can be rigid/semi rigid – flexible duct is not compliant
o Ducting to terminate at an adjustable supply/extract valve which enables balancing
at commissioning stage
 Ducting to the outside to exhaust stale air from the building and supply fresh air to the
MVHR unit
o Insulated as appropriate
 Boost switch (where applicable based on calculations)
 Control indicators must show occupier the unit is running or if a fault has occurred
o Control indicators must be in a visible location and not above the ceiling
 Extract/Supply rates to be designed as per the formulae in TGD Part F and the unit to be
commissioned to these rates, both by a competent person.
 O&M Manuals must be available to the occupant so that the system can be operated and
maintained correctly.
BENEFITS – Fully Part F compliant, improved indoor air quality, reduced heat loss compared to
other solutions, increased occupant comfort, less sound ingress from outside, fewer openings in
the building envelope, no additional Agrement certs necessary, commissioned using standard
airflow devices.

4. BROOKVENT, 38-39 Fitzwilliam Square, Dublin 2, D02 NX53, Ireland
T 01 546 1004 W brookvent.ie E hello@brookvent.ie
Other Methods of Compliance – Mechanical Ventilation
It is possible to use alternative methods of mechanical ventilation to achieve compliance with TGD
Part F. To achieve compliance these alternative systems will have to prove they can fulfil the
regulation as set out below
Adequate and effective means of ventilation shall be provided for people in buildings. This shall be
achieved by:
a) limiting the moisture content of the air within the building so that it does not contribute to
condensation and mould growth, and
b) limiting the concentration of harmful pollutants in the air within the building.
There is an onus on the manufacturers/suppliers of other methods of mechanical ventilation such as
DCV or Decentralised MVHR to provide the adequate documentation that demonstrates compliance
with the regulation above. This can be achieved by providing and Agrement cert.
Certain elements such as providing a control indicator and O&M manuals will still need to be
undertaken using alternative methods.
Specialist commissioning equipment may be necessary for the correct balancing of these systems. It
should be noted that ventilation validators may not have the necessary specialist testing equipment.
Applicable alternative methods include,
Demand Controlled Ventilation – DCV
This is essentially an MEV system with additional sensors and air volume control devices that react
to certain pollutants such as humidity and CO2.
They often include external wall grilles that open/close based on the humidity level in a room in
place of standard hit/miss wall grilles. This is to reduce heat loss at times when humidity levels are at
an acceptable level.
Specialist pressure-based tools may be necessary to commission the system.
DCV systems do not achieve any additional compliance benefits over MEV systems. Many standard
MEV systems will include humidity, presence, and CO2 sensors in addition to the standard,
compliant, operation features.
Decentralised Mechanical Ventilation with Heat Recovery – dMVHR
This is a ductless heat recovery system that includes small, oscillating, heat recovery units in each
room. It is necessary to link units together to ensure the supply/extract is in balance at all times.
While popular in buildings where ducting is not possible it can be costly to supply and install these
systems compared to traditional MVHR systems. Due to the number of units there can be an
increased maintenance and replacement cost incurred by building owners.
It must also provide control indicators for each unit to ensure compliance with TGD Part F.