GenAiration - Passivent

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GenAiration iMVHR
INTELLIGENT MECHANICAL VENTILATION WITH HEAT RECOVERY
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CI/SfB (57)
Uniclass L7513
March 2012

The intelligent solution 3
Standard MVHR systems 4
Passivent GenAiration 5
Features and benefits 6
Energy saving 7
The need to ventilate 8
Design features 9
Zonal control 10
System components 11
Further information 12
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Conventional MVHR
MVHR (mechanical ventilation with heat
recovery) systems recover part of the heat
lost through ventilation, so less energy is
used, less CO2 is emitted and heating costs
are reduced.
But conventional MVHR systems have
several disadvantages:
- The system is controlled by the user, who
must understand the system and remember
when to boost it.
- Some users may decide not to use the
boost, or even close ventilation valves, in a
mistaken attempt to save heating costs.
- The boost operates in all rooms at once,
whether needed or not, expending energy
unnecessarily.
- The boost is achieved by increasing the
fan speed, so increasing energy use.
All these factors can result in less effective
ventilation and cancel the advantages of heat
recovery.
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THE
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INTELLIGENT
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SOLUTION
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You’re at work
and the kids are at
school - home is
unoccupied
You’re home
from work and
start cooking
dinner
Dinner is
cooking whilst
it’s bathtime for
the kids
● Intelligent ventilation
Passivent GenAiration operates
intelligently – only ventilating at high
rates in the rooms where it is needed.
● Demand controlled
Humidity-sensitive extracts automatically
ensure that the system operates according
to demand, ie to the levels of humidity in
wet rooms. Boosts automatically when
needed
● No user control required
Users do not have to remember when to
boost, nor to understand the system.
Use of fixed position valves means users
cannot interfere with the operation.
GenAiration iMVHR
Passivent GenAiration is the fully automatic intelligent solution that needs no user intervention.
● Optimum performance
GenAiration operates according to
demand, achieving optimum ventilation
performance and optimum energy
efficiency.
● Fan energy savings
Changing ventilation levels is controlled
by the non-electrical adjustment of the
room extracts, not by the fan speed. There
is no increase in fan energy use when the
system boosts.
● Overall efficiency
As an extract opens to increase the
ventilation rate in that room, the
ventilation rate in other rooms reduces,
reducing ventilation heat loss while still
maintaining the overall required
ventilation.
● Meets regulations
Can be used to meet building regulations
for both ventilation and energy
conservation.
The GenAiration concept
Ventilation automatically matches demand in individual wet rooms using
humidity-sensitive extracts.
Total extraction rate for the home is constant, avoiding over-ventilation.
Kitchen Bathroom En-suite
Normal Normal Normal
Boost Normal Normal
Boost Boost Normal
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4
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GenAiration
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STANDARD
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MVHR
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SYSTEMS
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The current solution
The principle of MVHR systems is that they
recover a percentage of the heat lost through
ventilation, and supply it back in to the
home. This means that the primary heating
source, whether conventional combi-boiler,
heat pump or communal heating scheme,
should not need to work as hard to maintain
the ambient indoor temperature. Of course,
the main results are that less energy is used,
less CO2 is emitted to the atmosphere, and
heating costs are reduced for the occupant
or the scheme.
As we build more
airtight properties in
order to reduce heat
loss and save energy,
the need for
continuous
ventilation increases,
so as to ensure that
indoor air quality is
not affected and
reduce the risk of mould and damp within
our properties. An MVHR system is a
constantly running system, operating 24/7 to
reduce levels of pollutants within our
dwellings.
Shortcomings
Standard MVHR systems address the need
for recovering heat to reduce ventilation
energy loss, but they do pose some
operational issues.
Remembering to boost
The system is controlled by the user, who
has to remember to boost the system as and
when required. We are creatures of habit and
it can be difficult for people to remember to
do something when they are not used to
doing it.
Understanding when to boost
If the user fails to understand the system
then they can over- or under-boost it. Many
systems have 2 or 3 settings of operation,
and it can be confusing trying to establish
what level of boost should be used depending
on the activity and duration of moisture
production. Failure to select the right
setting can result in either over- or underventilating.
Deciding not to boost
Some occupants may decide not to boost the
system when required, as they perceive this
to increase energy usage with higher costs
and little benefit. For the same reason, they
may degrade the performance of the system
by closing extract valves – virtually cutting
off all air supply and extraction in the
dwelling.
The solution
The ideal solution is a system which does not
need user control - one that is fully
automatic. The user does not need to
remember or understand how to operate the
system, and can not adversely affect the
performance of the system either on purpose
or by accident.
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GenAiration
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PASSIVENT
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GenAiration
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THE
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INTELLIGENT
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SOLUTION
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What is it?
Passivent GenAiration is a ventilation system
with heat recovery which boosts
automatically when needed, meaning that
the user does not need to remember or
understand when to boost the system.
- Users can not interfere with the operation
of the system.
- They can not decide to under-ventilate in
a misguided attempt to save heating costs.
- They can clean the extracts without
affecting the performance of the system
How does it work?
A humidity-sensitive extract is located in
each wet room. As the extract senses that
there is an increase in relative humidity, it
opens up to allow more air to be extracted
out of the room. As relative humidity
decreases, the extract closes. There is no
user or occupant interaction required.
Stale air is exhausted via
roof terminals
Supply valves Warm moisture-laden
air is extracted from
Airflow from dry to wet rooms
wet rooms
DRY ROOMS
(eg living room,
bedrooms)
HR (heat recovery) unit with
constant speed fan
Energy consumption
Because the increase or decrease in
ventilation levels is controlled by the nonelectrical
humidity extract, and not, as in
standard MVHR systems, by the fan speed
increasing or decreasing, there is no increase
in fan energy usage when the system boosts.
As an extract opens – increasing the
ventilation rate in that room - the
ventilation rate in other rooms reduces, yet
still maintaining the overall required
ventilation rate.
Intelligent energy use
Passivent GenAiration intelligently uses
energy – only ventilating at high rates in
rooms where it is needed and not in those
rooms where it isn’t. In contrast, when
standard MVHR systems boost for one room,
they boost for all rooms whether needed or
not, expending more energy.
WET ROOMS
(eg bathroom,
kitchen)
Supply air is drawn in via roof terminals and
warmed in the HR unit using the heat from
the exhaust air
Ventilation rate is controlled by
humidity-sensitive non-electrical
extracts
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GenAiration
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FEATURES
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AND
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BENEFITS
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Passivent GenAiration has specific features
which provide further benefits over
standard MVHR systems.
● Humidity-sensitive extracts
Being fully automatic and non-electrical,
the extracts mean that there is no
requirement for the occupant to operate
the system. This removes the potential for
misuse through either forgetfulness, a
lack of understanding or deliberate lack of
use of the system boost.
These attributes make the system
particularly suitable for tenanted
properties, social housing or care homes.
● Non-adjustable valves
Adjusting the position of screw valves can
affect the performance of a standard
system, leading to over/under ventilation.
The non-adjustable valves of GenAiration
mean that the system performance can
not be affected by users when cleaning,
decorating or on purpose attempting to
achieve a perceived energy saving.
● Localised zonal control
Because the control of extraction rate is
zonal, ie by each humidity extract, only
the rooms needing to be ventilated more
are boosted. Traditional MVHR systems
boost the fan which increases the
ventilation rate in all rooms, even those
which are unoccupied and do not need
boosting.
● Non-commissionable valves
The extract and supply valves are noncommissionable,
meaning they do not
have to be adjusted during installation.
This reduces installation time and makes
installing the system simpler and more
efficient. This can lead to reduced cost of
installations for the customer, or allows
the contractor to undertake more work
and finish jobs quicker.
● Regulated airflow
The regulated airflow concept allows the
fan to run at a constant rate. It does not
need to run at a higher rate when
boosting, which can reduce energy
consumption compared with a standard
system and reduce wear on the motor.
Patent Pending.
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BENEFITS OF THE MVHR ELEMENT
● Heat recovery
MVHR recovers a percentage of heat from
wet rooms, which is used to pre-warm the
air that is supplied back in to the
dwelling. This can reduce the energy
consumption of the primary heating
source used to maintain the ambient
internal temperature.
● 24/7 Continuous ventilation
Operates 24 hours a day, 7 days a week to
ensure that air quality is maintained.
Research has shown that intermittent
systems can be ineffective in reducing
prolonged levels of high humidity
● Future-proof
Can be used in properties designed to
meet up to Code Level 6 of the Code for
Sustainable Homes.
ENERGY SAVING
Passivent GenAiration regulates airflow
within both the supply and extract air
stream. This feature enables the system to
self-regulate and remain balanced when
extracts boost to remove excess moisture
within the wet rooms.
This allows the system to boost
automatically without the need for a
separate fan boost, and remain balanced.
During commissioning the operational fan
speed is selected to achieve the required
whole-house ventilation rate. Once the
required rate is set, the system will continue
to operate at the same fan speed throughout
its operational life.
This means it uses a constant level of energy
to operate, not needing the fan speed to
ramp up considerably whilst boosting.
By using Passivent GenAiration the
ventilation energy usage can be reduced
against that of a standard MVHR system, as
the fan speed does not need to be increased
(consuming more energy).
Reducing energy usage reduces both carbon
emissions and energy costs.
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GenAiration
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THE
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NEED
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TO
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VENTILATE
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Energy-efficient ventilation
As we build our homes more airtight in
order to improve thermal efficiency, a
ventilation system becomes even more
important to ensure that moisture and other
pollutants are removed from the indoor
atmosphere.
Older dwellings relied heavily on fortuitous
ventilation, that is natural ingress and
extraction of air through gaps in the
construction. Modern homes are built to
reduce those gaps and so reduce fortuitous
ventilation. Instead a controlled, energyefficient
ventilation system is required.
Building Regulations
Regulations require ventilation (Approved
Document F1 Means of ventilation), and they
require that ventilation to be energy efficient
(Approved Document L1A Conservation of
fuel and power in new dwellings).
Passivent GenAiration systems can be used
to meet these regulations.
Energy efficiency in building
Within the UK, the method of measuring the
energy performance of a building, and so its
carbon emissions, is via the Standard
Assessment Procedure (SAP). This looks at
the energy usage and carbon emissions of
the building fabric and primary services.
Approved Document L1A gives guidance as
to the minimum performance of a building,
specified as the Dwelling Emissions Rate
(DER). These are based on the performance
of notional buildings.
The government, via the Code for
Sustainable Homes, gives a limit on the
amount of carbon emissions a property can
emit against the notional building in
Approved Document L1A, with the goal of
meeting Code Level 6 – zero carbon - by
2016.
Ventilation requirements
Approved Document F1 gives guidance on
ventilation of dwellings. It gives prescribed
rates of extraction and supply air needed to
meet the requirements. For mechanical
systems it specifies individual room rates
and a minimum whole house rate.
BBA Approval
This authoritative third
party approval shows that
the system meets
Building Regulations by meeting air quality
and moisture criteria specified by the
regulations. This method of approval can
allow for more energy-efficient
systems to be developed and used
whilst ensuring that occupant and
building health are not compromised.
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GenAiration
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DESIGN
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FEATURES
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Social and rented housing
Prior to developing the Passivent GenAiration
system we conducted research which
identified the concerns of specifiers and
landlords about some features of
conventional MVHR systems.
As a result of this we designed the system
particularly to meet these concerns.
The main area identified was that occupants
can affect the performance of a standard
MVHR system by adjusting the valves which
are located within wet and habitable rooms.
This is of great concern because it can lead
to issues affecting the structure and the
occupant.
Adjusting the valves of an MVHR system can
have a serious negative impact. Occupants
close the screw valves in habitable rooms
because they are perceived as causing
draughts, and in wet rooms because they are
thought to be wasting energy and money
by extracting heat.
Intrinsic to the design
In developing the system, one of
the key design briefs was to
provide a system which could
not be easily affected by the
occupant – to remove their
ability to have a negative impact
on the system performance. Passivent
GenAiration does that. The valves used in
both the wet and habitable rooms are nonadjustable,
meaning that occupants can not
close them up to restrict the performance
and operation of the system.
Standard MVHR systems require the use of
adjustable valves so that the required extract
and supply rates can be set in each room.
Every system is unique and so a fixedposition
non-adjustable valve would not
allow the required and most efficient rates to
be achieved.
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Installation benefit
A further benefit of using the non-adjustable
valves is that the time required to
commission the system is reduced
dramatically. A standard MVHR system
requires each individual valve to be set – and
setting one can affect the performance of
another. It is a timely and expensive
requirement.
Passivent GenAiration requires only a
fraction of the time to commission. The
engineer needs only to set the fan speed for
the main extract performance, usually the
kitchen extract; then the remaining extracts
within the wet rooms will set automatically.
For the supply side, adjustment is not
required at all.
This can reduce the installation time and
cost of each system and make it more user
friendly.
Fixed position Supply and
Extract valves
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GenAiration
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ZONAL
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CONTROL
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What is it?
Zonal control means controlling the demand
for ventilation in each specific ‘zone’ within
a dwelling. Within a domestic situation a
zone will be one particular room, for
example, a kitchen, bathroom, or utility
room. Zonal control is based on adjusting
the ventilation as necessary to suit the
requirement of each zone.
Humidity-sensitive MVHR systems are not a
new concept, indeed there are many systems
out there which offer this. However, they
work by sensing the amount of humidity in
the airstream within the system; when it
reaches certain set points the fan speed is
increased to quickly alleviate the excess
moisture within the system.
What a system like this can not do is
distinguish in which zone that excess
humidity is, and then only increase the
ventilation in that specific zone. Instead it
increases the fan speed which in turn
increases the ventilation rate in every zone –
even those which do not need it. It is
therefore working harder than is necessary,
consuming more energy than is necessary,
and extracting excess heat.
Passivent GenAiration is different: instead of
using a sensor within the heat recovery unit
and adjusting the fan speed, it uses humidity
sensitive extracts in each zone. As each
extract senses an increase in humidity it
opens up to allow a greater extract rate to be
achieved – importantly – only in the room
which requires it. The rate in other rooms is
not increased.
Passivent GenAiration zonal controlled
system
When the bath or shower is in use, only
the extract rate in that bathroom will
increase.
Other rooms not needing to boost
will not boost.
Standard MVHR or standard
humidity-controlled MVHR system
When one bath or shower room is in use,
the extract rate will boost in all wet
rooms, even those not being used.
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GenAiration
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Passivent GenAiration uses some of the most
advanced and effective ventilation
components on the market in order to
provide the ultimate heat recovery system.
Passivent HR1 Heat Recovery Unit
This is one of the most efficient units listed
in SAP Appendix Q. Its low operating power
coupled with high efficiency heat exchanger
means that it offers cost effective, energy
efficient ventilation. The compact unit size
means it takes up minimal space within the
dwelling yet still has a capacity of up to
145m 3 /h, making it suitable for most
apartments and small houses.
Passivent HR3 Heat Recovery Unit
Also listed in SAP Appendix Q, this is a larger
unit than the HR1, which allows it to be
used on larger properties. It combines low
energy usage and high heat exchange
efficiency for up to eight wet rooms.
Humidity-sensitive Extracts
The extracts used within the system are
unique to Passivent. They are humidity
sensitive, yet non-electrical and nonmechanical.
This means that they consume
no energy to operate and there are no
mechanical parts to break and fail. The
humidity sensing function is achieved
through the use of nylon bands which
expand or contract depending upon levels of
humidity - in turn opening and closing the
extract.
Supply Valves
Providing greater aesthetic appeal than
most traditional supply valves, those used
within the GenAiration system seamlessly
integrate into a building’s decor.
Furthermore, they are fixed, not allowing
occupants to alter the position.
Flexible installation
Passivent GenAiration provides flexible
installation options to allow the system to be
installed in almost all applications.
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One of the biggest limiting
factors with any
ventilation system is the
incorporation of ducting
within the dwelling
without encroaching on
valuable living space. With
that in mind Passivent
have designed the
GenAiration system to be
used with SRD75 semirigid
ducting.
SRD75 is a small bore,
semi-rigid ducting which
utilises central and extract
plenums to distribute air
around the dwelling. The
small bore ducting has an
external diameter of 75mm making it ideal
for fitting within ceiling or wall cavities in
place of traditional rigid ducting which is
usually larger and can require ceilings to be
lowered or obtrusive boxing-in of ducts.
Furthermore, as SRD75 utilises a single run
of ducting from the central plenum to the
extract plenum without the need to join
lengths of duct, the installation time of
ducting can be greatly reduced - by up to 50%.
Acoustic Advantage
The issue of cross talk is eliminated using
SRD75 ducting as there is a separate duct
run from the central plenum to each extract.
Conversation from one room is not
transferred through the ducting in to other
rooms, reducing occupant disruption.
Further specific information on SRD75
ducting is available from Passivent.
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FURTHER INFORMATION
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Mastercare Installer scheme
We recommend that installation is carried
out by a specialist Passivent Mastercare
Installer. The Mastercare scheme, operated by
Passivent Limited, comprises well-established
and reputable companies who have been fully
trained and assessed by Passivent Limited to
install any Passivent system in both new
build and refurbishment projects.
Mastercare provides:
● Assurance that work is carried out by
trained and experienced installers who are
familiar with the systems.
● Quality installations.
● Compliance with relevant codes of
practice.
● Competitive cost.
All Passivent Mastercare Installers hold a
certificate from Passivent Limited. They are
regularly monitored to ensure standards of
work are maintained, and also receive full
technical support from Passivent Limited.
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PASSIVENT LIMITED
2 Brooklands Road, Sale, Cheshire M33 3SS Tel: 0161-905 5700 Fax: 0161-905 2085
Email: info@passivent.com Web: www.passivent.com
Passivent Limited maintains a policy of continuous development and reserves the
right to amend product specifications without notice.
A member of the Building Product Design Group
Quality assurance
Passivent products are designed, developed
and manufactured under a BS EN ISO 9001
quality management system, giving an
independently audited assurance that the
products will fulfil their intended purpose.
Environment
Passivent conducts all business processes
under a BS EN ISO 14001 environmental
management system, giving an assurance
that all activities are carried out having
minimal impact on the environment.
Other products
Passivent market a range of other ventilation
solutions for domestic buildings including:
iHybrid: intelligent hybrid ventilation
iMEV: intelligent mechanical extract
ventilation
Intellivent: decentralised mechanical extract
ventilation
iHR: intelligent heat recovery ventilation
Background ventilation: full range of wall
and window vents
Acoustic ventilation
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Produced by Ted Hastings/Rackley Design