ADVICE & OPINION
STRIKING A BALANCE
FMJ AIMS TO SUPPORT TECHNICAL EXPERTISE IN THE FM MARKET
Martin Passingham, Product Manager at Daikin discusses how both improved
indoor air Tuality and a drive for increased building energy eƝ ciency can be
achieved by taking a whole-building approach to HVAC
In order to improve energy
e iciency, building air-tightness
has increased in recent years,
potentially having a negative impact
on indoor air quality (IAQ) if the
building HVAC system is designed
incorrectly.
The current requirements concerning
building e iciency are set to increase,
with the Government announcing
updates to the Building Regulations that
apply from June 2022. In the update,
CO emissions from new buildings,
including shops and o ices, are to be
reduced by 27 per cent compared to the
current standard. To address concerns
regarding IAQ, Approved Document F:
Ventilation also received an update. This
included indoor air quality monitoring
in all occupiable rooms in o ices, rooms
where members of the public gather
and rooms where ‘aerosol generating
activities’ take place, such as singing and
aerobic exercise. The changes do not
apply to small floor spaces, up to 50m‹,
and larger floor spaces, over 320m‹.
THE IMPORTANCE OF IAQ
The health risks associated with air
pollution are well understood and the
fact that people spend an estimated 90
16 MARCH 2022
per cent of their time indoors should
makes IAQ a key consideration.
Road tra ic, industrial processes,
waste incineration and construction
and demolition activities all generate air
pollutants, including particulate matter,
nitrogen dioxide (NO) and carbon
monoxide (CO). These substances, as
well as allergens such as pollen, can
be brought into a building through
natural or mechanical ventilation and
via inadequate filtration through the
building fabric.
There are also sources within a
building, including dust, damp, mould
and Volatile Organic Compounds (VOCs),
which can be given o by wall and floor
coverings, furniture and appliances,
and emissions from o ice equipment
and industrial machinery. Building
occupants also a ect IAQ, by exhaling
CO and spreading germs and viruses.
DESIGNING HVAC FOR IAQ
AND EFFICIENCY
When designing and specifying HVAC
systems, the main focus is o– en on
operational energy use and e iciency.
However, BREEAM also rewards the use
of HVAC that maintains high air indoor
quality by controlling temperature,
humidity and pollutants and ensuing
a su icient supply of fresh air for
occupants. By choosing the right
system there is an opportunity to
satisfy both requirements.
HEAT RECOVERY
The heat loss that occurs during the
exchange between indoor air and
fresh outdoor air is the primary issue
for energy e iciency with regard to
ventilation. To help minimise this,
e ective heat recovery implemented
into the system can further improve
the energy e iciency of the HVAC. For
example, in an o ice space, servers
can generate large amounts of heat.
With considered planning, this heat
can be reused elsewhere in the
building.
Manufacturers typically state
Seasonal Energy E iciency Rating
(SEER) figures of three and four for
heat recovery systems. However, it
is possible, for a system’s e iciency
ratio to nearly double under certain
conditions, when taking into
consideration recovered energy. In
reality, a SEER in excess of six could be
achieved frequently.
Utilising other technology within a
system, such as Variable Refrigerant
Temperature control, can lead to
further energy savings being made.
This varies the amount of refrigerant
flowing through the system and alters
the evaporating and condensing
temperatures to match demand. This
means significantly less energy is
needed and e iciency is increased.
PROTECTING SUPPLY AIR QUALITY
An important consideration is the
placement of ventilation intakes and
exhaust outlets on the exterior of the
building. To ensure that air is sourced
from the freshest supply, ventilation
intakes should be located as far away
from sources of outside pollution, such
as road tra ic, as possible. Typically,
the roof is preferred location unless
there is a pollution source at this level.
It is also important to avoid crosscontamination
from both boiler flues
and HVAC exhaust outlets. These should
be sited as far as possible from the
ventilation intakes.
FILTERS
To ensure good operation and maintain
energy e iciency, all HVAC units must
be fitted with filters that are designed
to keep them free of dust. Choosing
indoor units with auto-cleaning filter
capabilities ensures that dust can be
removed quickly and easily. This not
only prevents contaminants and odours
circulating in the room but also ensures
the unit operates e iciently.
Filters are also fitted to remove
particulate matter (PM) from supply air.
The type of filter required will depend
on what is needed to achieve the PM
threshold level. This is based on the
Air Quality Guidelines published by the
WHO. The recommended limits are: an
annual mean for PM2.5 of less than 10
micrograms per cubic metre (Ÿg/m3)
and an annual mean for PM10 of less
than 20 Ÿg/m¢.
ADDITIONAL MEASURES
Plasma ionisation technology can
help remove harmful particles, VOCs,
bacteria and viruses from the air. These
low-maintenance and cost e ective ‘fit
and forget’ units can be installed in new
or existing systems. While some plasma
ionisation devices have to be housed in
a separate unit due to their size, there
are options that are compact enough
to be fitted within the existing system
housing.
Airborne particles such as smoke,
dust, pollen and mould spores are
charged by the ions and stick together,
increasing their size and allowing them
to be captured easily, even by lower
grade filters. Meanwhile, bacteria and
virus cells bond with the oxygen ions
as they divide to reproduce and are
destroyed. Odorous gases and aerosols
are oxidised and neutralised on contact
with the ions. When the ions come into
contact with VOCs it causes a chemical
reaction that breaks down their
molecular structure.
When designed correctly, taking a
whole building approach to a HVAC
system can enable facilities managers to
minimise wasted heat and energy use,
whilst also delivering high quality levels
of indoor air quality.
FAST FACTS