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Energy Efficiency
- Home
- Energy Efficiency
Energy Efficiency
Thermal Performance
u-Value
Heat Gain & Heat Loss
Solar Heat Gain Co-efficient
Climate Zone & Zone Maps
is looking at ways of providing comfort and lifestyle as well as improving savings on energy costs in your home.
Glazing - glass windows and doors
Allows daylight into a building it enters through the glass (glazing) providing not only natural light but it also lets heat and cold enter - depending on the climate season.
- Are the most complex and interesting elements in the design of a building
- Provide light and fresh air to buildings and their occupants
- Can be a source of unwanted heat gain in the summer or unwanted heat loss in winter
- Windows can be designed to improve their performance in terms of heat gain and loss.
Unwanted heat gain and heat loss creates a major discomfort to occupants, as well as hurting their pockets in terms of energy for heating or cooling.
Energy Efficiency takes account of:
- Thermal transmittance "u-value" or "u-factor"
- Solar heat gain co-efficient (SHGC)
- Air leakage when shut
We measure the thermal performance of windows using some simple measures.
The measure for solar control is SHGC. SHGC is a measure of the window frame and glass to transmit solar energy into the room.
The measure for insulation is U-value. U-value measures the ability of the window frame and glass to conduct heat.
u-Value (uV)
We measure the thermal performance of windows using some simple measures.
The measure for solar control is SHGC. SHGC is a measure of the window frame and glass to transmit solar energy into the room.
The measure for insulation is U-value. U-value measures the ability of the window frame and glass to conduct heat.
U-value is the measure of heat loss or gain due to the differences between inside and outside air temperature. The lower the U value the better the insulating performance.
U-value measures the rate of hat flow through a window, driven by temperature difference across the window.
Heat Gain & Heat Loss
There are four ways in which windows and doors can gain and loss heat:
- Air inflitration (leakage)
- Radiation
- Heat convection
- Heat conduction
Heat loss and gain also occurs through cracks in window assembly and is measured in terms of the amount of air that passes through a unit area of window.
Air leakage can contribute to summer cooling loads in some climates by raising interior humidity levels.
Air infiltration (air-leakage when shut): The amount of air leaking in and out of a building through cracks in walls, windows and doors (natural ventilation).
Radiation: The transfer of heat in the form of electromagnetic waves from one separate surface to another. Energy from the sun reaches the earth by radiation, and a person's body can lose heat to a cold window or skylight surface in a similar way.
Condensation: The deposit of water vapour from the air on any cold surface whose temperature is below the dew point, such as cold window glass or frame that is exposed to humid indoor air. (Liquid forming on the windows)
Conduction: Heat transfer through a solid material by contact of one molecule to the next. Heat flows from a higher-temperature area to a lower-temperature one.
Convection: A heat transfer process involving motion in a fluid (such as air) caused by the difference in density of the fluid and the action of gravity. Convection affects heat transfer from the glass surface to room air, and between two panes of glass. Convection affects three areas - inside glazing surface, outside glazing surface and inside any air spaces between glazing.
Solar Heat Gain Co-efficient (SHGC)
The Solar Heat Gain Coefficient (SHGC) measures how well a window blocks heat from sunlight. The SHGC is the fraction of the heat from the sun that enters through a window. SHGC is expressed as a number between 0 and 1. The lower a window's SHGC, the less solar heat it transmits, and the greater its shading ability. The lower the number the better the product performs.
• SHGC = 1 implies all radiation travels through glass
• SHGC = 0 implies no radiation travels through glass
SHGC: The rate at which solar energy can penetrate the window.
SHGC can be expressed in terms of the glass alone or can refer to the entire window assembly.
SHGC is a measure of the ability of the window frame and glass to transmit solar energy into the room.
Simply: SHGC is a measure of how well a glass product blocks heat caused by sunlight.
Regardless of outside temperature, heat can be gained through windows by direct or indirect solar radiation. The ability to control this heat gain in terms of SHGC. Solar Heat Gain Co-efficient can be beneficial in winter but undesirable in summer.
Climate Zones & Zone Maps
To get the best energy savings and most comfort, different windows and doors are required for different climates.
Australia has many diverse climates, to make it easy it has been divided up into three (3) climate zones
• A Heating System for a cold climate - where the largest energy load is in heating the home. Reducing heat loss by retaining more heat inside, eg Melbourne, Hobart, Tamworth and Canberra is a typical cold climate.
• A Cooling System for a hot climate - where the largest energy load is in cooling the home. Reduction from heat gain retention of cool air by the heat from the outside, eg Brisbane, Cairns and Darwin are typically hot climates.
• A Mixed System for a mixed climate - Where the energy load is similar for heating and cooling, neither are dominant. Reducing heat loss by retaining more heat inside and reduction from heat gain retention of cool air by the heat from the outside, eg Sydney, Adelaide and Perth are typical of mixed climates.
Individual Australian State Maps
showing specific area zones relevant to suburb
Map source: Australian Building Codes Board: www.abcb.gov.au
A major principle of energy efficient building design is to allow the sun's heat into the home in winter while excluding it during the long hot days of summer. This can be achieved because the angle of the sun changes from season to season.
In summer the sun rises earlier, south of due east and climbs high in the sky before setting south of due west. Major summer heat gain occurs through the roof and through the east and west windows and walls of the home.
In winter the sun rises later, north of due east and stays low in the northern sky before setting north of due west. North facing windows and walls receive maximum winter sun and warmth.
You can achieve good passive solar performance at minimal cost if your site has the right characteristics. Where possible, choose a site that can accommodate north-facing daytime living areas and outdoor spaces.
Sites running North-South are ideal because they receive good access to northern sun with minimum potential for overshadowing by neighbouring houses. In summer neighbouring houses provide protection from low east and west sun.
North-South sites on the north side of the street allow north facing living areas and gardens to be located at the rear of the house for privacy.
North-South sites on the south side of the street should be wide enough to accommodate an entry at the front as well as private north facing living areas. Set the house back to accommodate a north facing garden.
Sites running East-West should be wide enough to accommodate north facing outdoor space. Overshadowing by neighbouring houses is more likely to occur on these sites.
A north facing slope increases the potential for access to northern sun and is ideal for higher housing densities. A south facing slope increases the potential for overshadowing.
The ideal orientation for living areas is within the range 15ºW-20 ºE of true or 'solar' north. 20ºW-30ºE of true north is considered acceptable.
Source: www.greenhouse.gov.au/yourhome/technical/fs13.htm
Samples of how the sun's energy is absorbed by glass (courtesty of Viridian Glass
)
ComfortPlus Glass
ThermoTech Glass
Trend Products
Energy Efficiency
- Home
- Energy Efficiency
Energy Efficiency
Thermal Performance
u-Value
Heat Gain & Heat Loss
Solar Heat Gain Co-efficient
Climate Zone & Zone Maps
is looking at ways of providing comfort and lifestyle as well as improving savings on energy costs in your home.
Glazing - glass windows and doors
Allows daylight into a building it enters through the glass (glazing) providing not only natural light but it also lets heat and cold enter - depending on the climate season.
- Are the most complex and interesting elements in the design of a building
- Provide light and fresh air to buildings and their occupants
- Can be a source of unwanted heat gain in the summer or unwanted heat loss in winter
- Windows can be designed to improve their performance in terms of heat gain and loss.
Unwanted heat gain and heat loss creates a major discomfort to occupants, as well as hurting their pockets in terms of energy for heating or cooling.
Energy Efficiency takes account of:
- Thermal transmittance "u-value" or "u-factor"
- Solar heat gain co-efficient (SHGC)
- Air leakage when shut
We measure the thermal performance of windows using some simple measures.
The measure for solar control is SHGC. SHGC is a measure of the window frame and glass to transmit solar energy into the room.
The measure for insulation is U-value. U-value measures the ability of the window frame and glass to conduct heat.
u-Value (uV)
We measure the thermal performance of windows using some simple measures.
The measure for solar control is SHGC. SHGC is a measure of the window frame and glass to transmit solar energy into the room.
The measure for insulation is U-value. U-value measures the ability of the window frame and glass to conduct heat.
U-value is the measure of heat loss or gain due to the differences between inside and outside air temperature. The lower the U value the better the insulating performance.
U-value measures the rate of hat flow through a window, driven by temperature difference across the window.
Heat Gain & Heat Loss
There are four ways in which windows and doors can gain and loss heat:
- Air inflitration (leakage)
- Radiation
- Heat convection
- Heat conduction
Heat loss and gain also occurs through cracks in window assembly and is measured in terms of the amount of air that passes through a unit area of window.
Air leakage can contribute to summer cooling loads in some climates by raising interior humidity levels.
Air infiltration (air-leakage when shut): The amount of air leaking in and out of a building through cracks in walls, windows and doors (natural ventilation).
Radiation: The transfer of heat in the form of electromagnetic waves from one separate surface to another. Energy from the sun reaches the earth by radiation, and a person's body can lose heat to a cold window or skylight surface in a similar way.
Condensation: The deposit of water vapour from the air on any cold surface whose temperature is below the dew point, such as cold window glass or frame that is exposed to humid indoor air. (Liquid forming on the windows)
Conduction: Heat transfer through a solid material by contact of one molecule to the next. Heat flows from a higher-temperature area to a lower-temperature one.
Convection: A heat transfer process involving motion in a fluid (such as air) caused by the difference in density of the fluid and the action of gravity. Convection affects heat transfer from the glass surface to room air, and between two panes of glass. Convection affects three areas - inside glazing surface, outside glazing surface and inside any air spaces between glazing.
Solar Heat Gain Co-efficient (SHGC)
The Solar Heat Gain Coefficient (SHGC) measures how well a window blocks heat from sunlight. The SHGC is the fraction of the heat from the sun that enters through a window. SHGC is expressed as a number between 0 and 1. The lower a window's SHGC, the less solar heat it transmits, and the greater its shading ability. The lower the number the better the product performs.
• SHGC = 1 implies all radiation travels through glass
• SHGC = 0 implies no radiation travels through glass
SHGC: The rate at which solar energy can penetrate the window.
SHGC can be expressed in terms of the glass alone or can refer to the entire window assembly.
SHGC is a measure of the ability of the window frame and glass to transmit solar energy into the room.
Simply: SHGC is a measure of how well a glass product blocks heat caused by sunlight.
Regardless of outside temperature, heat can be gained through windows by direct or indirect solar radiation. The ability to control this heat gain in terms of SHGC. Solar Heat Gain Co-efficient can be beneficial in winter but undesirable in summer.
Climate Zones & Zone Maps
To get the best energy savings and most comfort, different windows and doors are required for different climates.
Australia has many diverse climates, to make it easy it has been divided up into three (3) climate zones
• A Heating System for a cold climate - where the largest energy load is in heating the home. Reducing heat loss by retaining more heat inside, eg Melbourne, Hobart, Tamworth and Canberra is a typical cold climate.
• A Cooling System for a hot climate - where the largest energy load is in cooling the home. Reduction from heat gain retention of cool air by the heat from the outside, eg Brisbane, Cairns and Darwin are typically hot climates.
• A Mixed System for a mixed climate - Where the energy load is similar for heating and cooling, neither are dominant. Reducing heat loss by retaining more heat inside and reduction from heat gain retention of cool air by the heat from the outside, eg Sydney, Adelaide and Perth are typical of mixed climates.
Individual Australian State Maps
showing specific area zones relevant to suburb
Individual Australian State Maps
showing specific area zones relevant to suburb
Map source: Australian Building Codes Board: www.abcb.gov.au
A major principle of energy efficient building design is to allow the sun's heat into the home in winter while excluding it during the long hot days of summer. This can be achieved because the angle of the sun changes from season to season.
In summer the sun rises earlier, south of due east and climbs high in the sky before setting south of due west. Major summer heat gain occurs through the roof and through the east and west windows and walls of the home.
In winter the sun rises later, north of due east and stays low in the northern sky before setting north of due west. North facing windows and walls receive maximum winter sun and warmth.
You can achieve good passive solar performance at minimal cost if your site has the right characteristics. Where possible, choose a site that can accommodate north-facing daytime living areas and outdoor spaces.
Sites running North-South are ideal because they receive good access to northern sun with minimum potential for overshadowing by neighbouring houses. In summer neighbouring houses provide protection from low east and west sun.
North-South sites on the north side of the street allow north facing living areas and gardens to be located at the rear of the house for privacy.
North-South sites on the south side of the street should be wide enough to accommodate an entry at the front as well as private north facing living areas. Set the house back to accommodate a north facing garden.
Sites running East-West should be wide enough to accommodate north facing outdoor space. Overshadowing by neighbouring houses is more likely to occur on these sites.
A north facing slope increases the potential for access to northern sun and is ideal for higher housing densities. A south facing slope increases the potential for overshadowing.
The ideal orientation for living areas is within the range 15ºW-20 ºE of true or 'solar' north. 20ºW-30ºE of true north is considered acceptable.
Source: www.greenhouse.gov.au/yourhome/technical/fs13.htm
Samples of how the sun's energy is absorbed by glass (courtesty of Viridian Glass )
ComfortPlus Glass
ThermoTech Glass