The Benefits of Thermal Ventilation
A building’s air conditioning system is typically responsible for around 50% of
the base building’s energy consumption. The other 50% typically includes other
services such as common area lighting, domestic hot water, lifts, etc. As such,
any reduction in air conditioning energy consumption or efficient energy
utilisation will offer significant savings in total building energy consumption
and carbon emissions.
Night
purging, displacement ventilation, Positive input ventilation with 100% fresh
air intake (Solar air collectors), high thermal mass materials and a
co-generation plant be adopted to significantly contribute to the health of
occupants, the reduction of carbon dioxide emissions and reduce energy
consumption of the building.
The use
of all these initiatives will reduce carbon emissions to 44% of a 4.5 star
Australian Building Greenhouse Rated building.
Building
loads determine the heating and cooling requirements of a building and come
from sources such as occupants, equipment, lighting and the sun.
A typical large-scale building can have
hourly energy loads up to the following – lighting 95 kWh, occupants 45 kWh,
Equipment 155 kWh, (summer solar 60-110 kWh, mid-winter 30-65 KWh). On a
monthly basis this could lead to a mean usage of between 60,000 and 80,000 kWh.
Using a thermal (Solar air collector) panel
system for both night flushing for cooling and daytime solar absorption for
heating introduces 100% fresh air into the building, thereby flushing out all
contaminated air without mixing. This greatly increases air quality, health
wellbeing and productivity of all its occupants. Following this, maintenance
costs are greatly reduced due to minimal hourly use of boilers/chillers.
As
most large-scale buildings are built on concrete and other reasonably good thermally
absorbing materials, they are capable of storing and releasing large amounts of
energy (sensible heat). Put simply, in summer - the building will store the
coolness of the night and use it to cool the building during the day. In
winter, the building will attain the solar heat energy and use it to maintain
higher core temperatures at night.
“Thermal
mass, correctly used, moderates internal temperatures by averaging out diurnal
(day/night) extremes.
Poor use of thermal mass can exacerbate the worst
extremes of the climate and can be a huge energy and comfort liability.” #i
The intent
of a ‘green’ building is to minimise the emission of greenhouse gases, namely
carbon dioxide emissions through efficient energy usage. This is will be dependent
on energy utilisation between sources such as electricity, gas, solar, wind or
energy from a co-generation plant, etc
Ban Ki Moon has stated,
“Leaders must act. Time is not on our side.” He said that quick,
decisive action would build a better and sustainable future, while inaction
would be costly.
“The building’s of our cities are our businesses, the
businesses of our cities are our leaders, and it is time for simple cost
effective change.” EC
In the
state of Victoria, Australia, gas has a CO2
co-efficient
of 0.21, which is much less than the 1.34 co-efficient for electricity. This
means that electricity pollutes about 6.4 times more than gas and electricity
usage is most undesirable. #ii
It is
obvious that using thermal passive input ventilation system with 100% fresh air,
improves longevity and cost effectiveness of the system. In this ventilation
system offers advantages such as: -
·
Carbon emissions –
reducing CO2 emissions to 40% of
a 4.5 star building
·
Air quality – by providing 100%
fresh, non-recycled air, as well as using the benefits of continuous
ventilation to flush warm contaminated air out instead of mixing it within the
space
·
Equality of access – all
occupants have access to the cool ceiling above and floor vents are evenly
distributed which passively proves a more even temperature throughout the space
·
Increased productivity – through
the reduction of noise, the increase in air quality, and the even distribution
of cool air, occupants are healthier, more comfortable, have an increased state
of wellbeing and are more productive.
·
Maintenance – is much less for
chilled night flush system as there are less moving parts
·
Increased lifespan – the
chilled night flush system has an increased lifespan because of reduced plant
loads and less maintenance problems
·
Space saving – Thermal heat and
night flush (Solar air collectors) systems eliminate the need for additional
internal high volume ductwork, minimising ceiling voids requirements and
increasing opportunities for refurbishment as well as increasing net leasable areas
opportunities, all solar air collector systems can be retro fitted and adapted
to existing air ventilation systems.
·
Energy efficiency.
Friction losses and lagging are eliminated by the system and the building
fabric contributes to the cooling system.
·
De-humidification. With
solar air collectors, all daytime air has the enormous benefit of de-humidification,
greatly reducing the possibility of increased condensation.
To
improve a building’s energy savings even more, the use of secondary external
shading to Northern/Western walls, use of thermal (light colours) paints and
external screening/shading to glazed areas.
Further
information on solar air collectors can be found at http://www.solarventi.com.au/index.php/professional
Or http://www.solair.com.au/solarventi-air-collectors.php
# i - http://www.yourhome.gov.au/passive-design/thermal-mass
# ii
- http://www.melbourne.vic.gov.au/Sustainability/CH2/DesignDelivery/Documents/CoolHeat_AirConditioningDesignStrategy.pdf
By Eamon
Corless - Jan. 2015
