This project has been assisted by
the New South Wales Government
through its Energy Efficiency Training Program
Sustainability Program for Community
Housing Organisations
Compass Housing Services
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2
Thermal performance
• How energy comes into,
around and out of our
homes
• Maintaining interior
comfort levels
• 78 images
• How behaviour can
heavily influence energy
and cost
• Largely determined by
building design
Achieving thermal comfort
Thermal comfort is
achieved by having your
body in equilibriumthe heat coming onto
the body matches the
heat leaving the body.
Thermal comfort is subjective
People feel heat differently
Generally,
People from the UK find the climate here very
warm – hot
People from the equatorial countries- i.e. Singapore
generally find climate here cool.
How we are conditioned can have a big effect on
heating or cooling costs.
Heating and cooling expectations are now much
greater then they used to be.
Image credit: ecoheat SA.
Heat Movement
It is important to understand the 4 methods of heat transfer.
• Radiation. Heat transfer through space, and heating only
the object that catches the radiation
• Convection. The movement of air due to the fact that
warm air is lighter than cool air.
• Conduction. Heat transfer through direct contact between
warm and cool objects.
Evaporation
The other major method of heat exchange,
• It is extremely effective at cooling
• Water absorbs a very large amount of heat (2.3MJ/litre)or .6KWh/l
That is why
• Sweating is so effective,
• Breezes are so refreshing in summer.
Evaporation depends on lower levels of humidity.
• That is why evaporative air conditioners are common inland
• But not along the relatively humid coastal strip.
Passive solar designWhat is it???
A method of controlling the internal temperature of a building
by using appropriate design principles.
Features of passive design?
• Creates comfortable living conditions while avoiding the use
of expensive appliances for heating and cooling
• Free heating from the sun during winter
• Shielding house from sun in summer keeping it cool
• Makes use of the cooling breezes in summer
• Passive because the house design self regulates temperature
• The best results are gained by active occupants
Seasonal variation of the Suns path
Ideally a long face of the building faces north for maximum solar
control
• Note shadow length and angle of sun.
• Many streets-full of existing houses are already orientated the
right way, and are relatively easily adapted.
Passive solar design
Image: Yourhome.gov.au
….. the major features
Thermal mass- examples
MATERIAL
THERMAL MASS
(volumetric heat capacity, KJ/m³.k)
Water
4186
Concrete
2060
Sandstone
1800
Compressed earth blocks
1740
Rammed earth
1673
FC sheet (compressed)
1530
Brick
1360
Earth wall (adobe)
1300
AAC
550
Source: EDG
Eaves and solar control
http://www.yourhome.gov.au/technical/fs45.html
Essential features for passive solar
function
• Correct orientation of windows -for allowing or rejecting
solar heat. (Mostly on north side)
• Ventilation for summer cooling
• Thermal Mass for storing heat or cool
• Insulation to resist heat flow- in , or out
• Shading by eaves and vegetation -sun control
Reverse Brick Veneer
Reverse brick- veneer is a perfect building system to use in
mixed climate zones.
A mixed climate zone is where it is often too hot in the
summer, and too cold in the winter i.e. most of southern
Australia.
General Layout priorities
Credit: yourhome
•
•
•
•
•
East– west orientation, with long face either front or back
Living rooms toward the north side
Lesser used rooms to the southMore windows to the north, easy solar control
Less windows to the W, E, and least to the south.
Design exampleEvery room has solar access
North
•
•
•
•
Credit: Ian Garradd, Madhan Sekar
Large windows along north face
Thermal mass along front for heat control
Windows allow breezes
With good insulation, energy bills close to ZERO for heating and cooling
Site analysis and solar potential zero
energy home. -A feasibility study, Tasmania.
Images: Ian Garradd
• All energy and water
could come from the
building
Eventually all buildings are likely to be
carbon neutral in their operation
Images: Henley Homes, Delfin, Lend -Lease
This is one recently built in Melbourne by some progressive
developers.
…It looks just the same as any other well- designed home.
Compass north is not true north
Credit: yourhome
Credit: Google earth
The best orientation for passive solar design is TRUE north, or
GRID north, often referred to as SOLAR north
Does it apply to existing buildings?
While in practice, we will be mostly dealing with existing
housing, it is essential to be familiar with the major elements of
natural heating and cooling….
• as it is possible to adapt most buildings to harness at least
some of the free heating and cooling potential.
• It is important to consider passive solar energy potential
when either buying , or renting a house, as it will have a large
impact on the cost of living of the occupant$.
Building energy ratings to come
Image: Wikimedia commons.
(in the ACT)
• Indications of energy required to keep house interiors comfortable
• The A.C.T. has been using mandatory energy ratings since 1999
National home energy ratings
What the stars mean
• Zero stars means the building shell does practically nothing to
reduce the discomfort of hot or cold weather.
• A 5 star rating indicates good, but not outstanding, thermal
performance.
• Occupants of a 10 star home are unlikely to need any
artificial cooling or heating.
What effect do various design features
affect energy and thermal comfort?
Credit: Ian Garradd
Energy from the sun
• Summer sun radiation approx. 1000 watts/ m2
• That’s why you want to bock it out
• Winter sun approx. 500 watts / m2
• That’s why you want to let it in
“It seems to me that we all look at Nature too
much, and live with her too little.”
Oscar Wilde, "De Profundis", 1905
Houses will be more comfortable if we make the most of what
nature can offer
Sun control begins in the garden
Credit: Ian Garradd
• The trees provide a HUGE benefit for summer cooling
• Keep north windows unshaded to allow winter sun into windows
• More comfortable interiors, cheaper to run
Thermal mass
• Heavy, massive materials have large heat capacity.
• Internally, they can retain very useful warmth, or coolth.
• Exposed, i.e. not carpeted surfaces are best- i.e. tiles, brick, etc.
Winter
Summer
Credit: yourhome
• Thermal mass inside a
house reduces daily
temperature fluctuation
Credit: Ian Garradd
Design features for summer comfort
Street frontage faces north, season- mid summer
• Large north facing windows with wide northern eaves
• Keeps the summer sun out, but lets the winter sun in.
• What effect will happen on the west windows/ wall in pm?
Image: Nearmap.com
Roof colours
• White coloured roofing is around 30 degrees cooler than dark
• Where is a large part of the heat going to end up?
• Reliance on air conditioning?
Trees for cooling
Image: yourhome.gov.au
1. Trees are essential for controlling temperature in and around
the home
2. The yard is far more pleasant with the cooling effect of trees
3. An extremely low cost solution for summer cooling
4. If tank water is available, put the sprinkler through the leaves
on for free air conditioning
Image: Ian Garradd
Keep the sun off the glass in summer
East facing house
If glass gets hot, heat is already heading inside
• External shading is far better than internal shading – blinds, etc.
• External shutters
• External awnings
• External roller blinds
Comparison of heat gains through different window treatments
Image: Sustainability Victoria
Awnings
• Best for east or west walls
• Ensure a heat-reflective fabric
is specified
• Leave up in winter to let
winter heat in
• Needs occupant motivation
to control it
• Awning should extend
beyond window frame , i.e.
approx. 300 mm each side
Image: Ian Garradd
Insulated and lined verandas
Image: Ian Garradd
• A verandah, eave, or awning with insulation transmits
negligible heat.
• This will heavily impact on interior temperatures, as
much of the heat which comes through as radiation goes
through the walls and windows to the interior.
Reflective foil insulation
• Generally put under
sheeting and tiles but
retrofitting easier under
rafters.
• A more effective and
safer method of
retrofitting foil (just a
bit more effort)
2 main categories of insulation….
Reflective foil is most suited to keeping heat out in summer
Thick blanket insulation is for keeping heat inside
They are both essential for year –round comfort
Night purging and breezes
• Landscaping to
direct cooling
breezes
Image: yourhome.gov.au
• Allow crossventilation to do most
of the cooling with
sea breezes, or night
breezes
• Requires vigilance
roof vent ilat or
exhaust fan
ceiling fan
closable inlet
vent for roof
vent ilat or
fully openable
window area
sealable
high wall
vent s
openings on
opposit e sides
of house
closable inlet vent
for exhaust fan
minimal obst ruct ions
bet ween openings
Met hods of achieving air movement in a house.
Be familiar with useful breezes
Wind roses showing local summer breezes at 9am and 3pm
Strong afternoon cooling breezes from the East and South-East
Security screens
• Security screens essential
in many cases so that
people can relax while
leaving doors and windows
open for summer cooling.
The Stack Effect for summer cooling
• Allows warm air to
leave the house by
convection
• Open windows and
doors in summer
• Operable skylights are
also excellent for this
Image: US dept. of housing
Cross–flow for most effective cooling
• In the front door and
out the back,
• Or open whatever
combination of
windows and doors
can achieve air flow
through most of the
house, or warm
rooms.
The more breeze options the better.
Whirlybirds
Image: Nearmap.com
Image: Ian Garradd
Exercise:
200 m2 dark roof tiles….
•Calculate the load at any one time
•How much difference will 1 whirlybird make?
Maximise cooling potential for hot
weather
Always use natural breezes instead of appliances to keep cool if possible
A better solution
Image: Ian Garradd
• White roof,
• Multiple industrial size whirlybirds
This combination has a large impact on internal temperature
Effective venting of warm air from
interior
Operable skylights
• Remove heat from
ceiling level
• Available with
double glazing,
thermal
treatments, and
blinds.
• Highly effective and
versatile
Image: Ian Garradd
Summer climate control review.
• Each person to recount an experience of an aspect of a
home, where it was too hot.
• Explain what you would do about it - in hindsight
• Summarise the main aspects of heat control.
Break 5 min