Introduction
History
The concept of Sustainability began in the 1960's with numerous authors exploring the concern of how environmental actions in the present affect the "Ability of future generations to meet their own needs".
The model of Sustainability progressed into international forums throughout the 1970's. The United Nations Conference on the Human Environment in 1972, and Habitat in 1976 discussed the "need for a changed approach to development". "In 1987 the World Commission on Environment and Development, in a report titled Our Common Future (the Brundtland Report), recognised that sustainable development meant adopting lifestyles within the planet's means."
By 1992, The Agenda 21 publication was produced as a result of the United Nations Conference on Environment and Development (commonly referred to as the Earth Summit) in Rio de Janeiro. The Agenda 21 "sets out a blueprint for sustainable activity across all areas of human endeavour."
The National Strategy for Ecologically Sustainable Development was developed in Australia as a result of Agenda 21 in 1992 and the Australian Department of the Environment, Water, Heritage and the Arts Ecologically Sustainable Development work to date has focused on implementing the recommendations of strategy as well as Agenda 21. There were extensive discussions between key interest groups over a two year period from 1990 which contributed to the strategy. As a result the following principles were identified:
Integrating economic and environmental goals in policies and activities;
Ensuring that environmental assets are properly valued;
Providing for equity within and between generations;
Dealing cautiously with risk and irreversibility ; and
Recognising the global dimension.
The various levels of government have undertaken this strategy 'according to its own needs and priorities. Legislation and government programs increasingly stress ESD objectives and principles.
Sustainability in the Construction Industry
The concept of sustainability in regards to environmental design for our built environment is to create buildings that are comfortable and healthy, use no energy, no water, produce no waste in operation or construction, and are made of materials that are derived from fully sustainable sources. Whilst some of these aspects are difficult to achieve in practice, this aim should act as a backbone for the opportunities that should be considered in any project.
"Buildings have a major influence on energy consumption in both the residential and commercial sectors." The amount of energy used in both sectors is a major contribution to peaks in electricity demand, particularly with the increased reliance on air conditioning. Every new building constructed without incorporating sustainable energy features creates a long-term financial and environmental liability.
There are many methods and materials which can be used for a development to be more sustainable, through principles as mentioned in Section 2. The Department of Sustainability and Environment (DSE) which is a part of the Victorian state government has developed Environmentally Sustainable Design and Construction (ESDC) Principles and Guidelines to "integrate environmental sustainability into the planning, design and construction processes for all new capital works." The department cites the following principles:
Energy Conservation
Water Conservation
Minimisation of Fossil Fuel Usage Associated with Transport
Preserve Natural Features of Site
Building Materials Conservation
Waste Minimisation
Enhancement of Indoor Environmental Quality
Appropriate Landscaping
Enhance Community Life
Maintenance
The department also emphasises that all Government agencies need to be aware of the impacts of our activities on the environment. Simply by building and operating our facilities we risk having adverse impacts such as:
Production of greenhouse gases through the use of energy sources such as electricity, natural gas and LPG
Wastage of water through inefficient fixtures and fittings
Production of waste contributing to landfill through building, construction and operational activities
Impacts on a site's indigenous flora and fauna
Excessive use of energy in transport
These guidelines are to be implemented on all capital works by State Government Departments in design and construction activities. Though there isn't a way to measure the ecological effects from design and construction, "Benchmarking data is available for energy, water, waste creation and transport for conventional Departmental buildings, together with a variety of schemes for measuring and rating the environmental sustainability of building projects."
The guideline continues to state: "As a minimum, the ecological impact of capital works associated with energy consumption, waste production, water consumption and fossil fuels associated with transport should be decreased by at least one third in comparison with a conventional design, construction and occupancy process." And these impacts can be measured with the above benchmarking data.
Passive Design Elements
Design for daylight
DAVE
Orientation and planning
DAVE
Natural ventilation
ANDREW
Insulation and glazing thermal performance
DAVE
Thermal mass & Glazing placement and shading
DAVE
Building sealing
"The building envelope must control air leakage through wall and ceilings junctions and treatment of penetrations such as chimneys and exhaust fans new provisions apply to sealing evaporative coolers."
Building Sealing standards are required to be implemented to a Class 2 to 9 building, other than:
In climate zones 1, 2, 3 and 5 where the only air-conditioning is by an evaporative cooler
A permanent ventilation opening for the safe operation of a gas appliance
A Class 6, 7, 8 and 9b without conditioned spaces
A building or space where the Part F4 ventilation provides pressurisation to prevent infiltration
An atrium or the like that is not a conditioned space and is separated by an envelope
Solar Chimneys and flues provide interior cooling and heating to balance conventional climate control systems. 'The heated air escapes out the top of the chimney and is replaced by air from the outside (through windows or vents elsewhere in the building). In winter the chimney vents to the outside can be closed and heated air in the chimney forced (using fans or other air handling system) into the building for heating purposes.'
'Solar chimneys are most effective in hotter climates with high cooling load.
Sunrooms can also be designed to function like solar chimneys.'
All external doors and windows are to be fitted with a seal to 'restrict air filtration' and water as per Clause J3.4. Sealing materials such as foam or rubber compressible strips should be fitted. 'The external doors must be self closing so that when not in use the loss of conditioned air is minimised.'
There are 3 different types of weather stripping:
woven piles
flaps;
and hollow or foam bulbs
"Which is best? That depends on the window style, design and application."
Roof lights serving conditional areas are required to be sealed and have a shutter system implemented.
Exhaust fans are can be energy efficient by "reducing fan pressures by limiting maximum filter pressure drops through regular maintenance, and though optimal duct design and installation. "
Construction of roof, walls and floors in an external capacity must be "Sealed to minimise air leakage".
This is achieved by installing "conventional internal fixing and lining systems" to:
Ceilings, wall and floor junctions
Any penetrations for wiring, piping etc
Passive solar heating
Descriptions:
In Passive systems (or thermosiphon systems) the tank is installed above the solar collectors so that cold water sinks into the collectors, where it is warmed by the sun, and rises into the tank. A continuous flow of water through the collectors is created without the need for pumps.
Passive systems come in two types: closed-coupled andgravity feed.
In a close-coupled system the horizontal storage tank is mounted directly above the collector on the roof. Heated water is provided at mains pressure. This arrangement is the most cost effective to install but efficiency is reduced in cool and cold climates by heat loss from the tank. Additional insulation of tanks is desirable in these climates. Alternatively, tanks can come away and moved inside the roof space.
In a gravity-feed system, the storage tank is installed in the roof cavity. These systems are cheapest to purchase but household plumbing must be suitable for gravity feeding, including larger diameter pipes between the water heater and the taps. A common alternative is to use closed circuit gravity feed system to heat mains pressure water using a heat exchanger.
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Benefits:
Easy to design and install into a new home or addition.
Proper for all climates where winter heating is required.
Achievable when building or renovating on any site with solar access
Achievable when buying a project home, with correct orientation and slight floor plan changes.
Achievable when choosing an existing house, villa or apartment. Look for goodorientation and shading.
Achievable for all types of Australian construction systems.
How passive solar heating works
The north facing windows expose to full sun by using solar radiation traps. Window frames and glazing type have a significant effect on the efficiency of this process.
Trapped heat is absorbed and stored by materials with high thermal mass (usually masonry) inside the house. It is re-released at night when it is needed.
Passive shading allows maximum winter solar gain and prevents summer overheating.
Heat is re-radiated and distributed to where it is needed. Direct re-radiation is the most effective means. Heat is also conducted through building materials and distributed by air movement. Heat loss is minimised with appropriate window treatments and well-insulated walls, ceilings and exposed floors. Thermal mass must be insulated to be effective. Slab-on-ground edges need to be insulated if located in climate zone 8, or when in-slab heating or cooling is installed within the slab.
Air infiltration is minimised with airlocks, draught sealing, airtight construction detailing and quality windows and doors.
Passive solar design principles
Greenhouse (glasshouse) principles
Passive design depends on greenhouse principles to trap solar radiation.
Heat is gained when short wave radiation passes through glass, where it is absorbed by building elements and furnishings and re-radiated as long wave radiation. Long wave radiation cannot pass back through glass as easily.
Orientation for passive solar heating
For best passive heating performance, daytime living areas should face north.
Ideal orientation is true north and can be extended to between 15° west and 20° east of solar north.
Passive solar shading
Fixed shading devices can maximize solar access to north facing glass throughout the year, without requiring any user effort. Good orientation is essential for effective passive shading.
Fixed shading above openings excludes high angle summer sun but admits lower angle winter sun.
Planning and design
Floor planning
Floor plan shows the heating requirements that the rooms in the house needed.
Locating heaters
Internal thermal mass walls are ideal for locating heaters next to. Thermal lag will transfer heat to adjoining spaces over extended periods.
External wall locations can result in additional heat loss, as increasing the temperature differential between inside and out increases the rate of heat flow through the wall. Heaters should not be located under windows.
Locating thermal mass
As a first priority, locate thermal mass where it is exposed to direct solar radiation or radiant heat sources. Thermal mass will also absorb reflected radiant heat.
Additionally, thermal mass should be located predominantly in the northern half of the house where it will absorb most passive solar heat.
Air movement and comfort
Air movement creates a cooling effect by increasing the evaporation of perspiration. Draughts increase the perception of feeling cold.
Avoid convection draughts by designing floor plans and furnishing layouts so that cooled return air paths from windows and external walls to heaters or thermal mass sources are along traffic areas (hallways, stairs, non-sitting areas).
Create draught free nooks for sitting, dining and sleeping.
Use ceiling fans to circulate warm air evenly in rooms and push it down from the ceiling to living areas. For low ceilings, use fans with reversible blade direction.
Sub-conclusion
WTE
Energy
Lighting
MARK B
Heating
ANDREW
Cooling
ANDREW
Hot water heating
Water heating is needed to for human consumption for many activities such as laundry, cooking, cleaning, washing, etc. Having a good water heating system is the important key to save energy, money and reduce green house gas emissions.
Storage and continuous flow systems
There are 2 main types of hot water systems:
Storage systems
Storage systems hold hot water in an isolated tank to be ready for use during the day. Fuels can be used such as natural gas, electricity, LPG, solid fuels, with or without solar. The most economical types of storage systems are natural gas and off-peak electric. Main pressure units are normally placed a ground level, either internally or externally. Constant pressure systems supply hot water at a lower pressure than mains pressure systems. They are usually located in the roof space of a home. The main advantages of constant pressure are that systems are much cheaper to purchase and have much longer life expectancies than mains pressure systems. These systems are also known as gravity feed or low-pressure systems.
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Figure : Storage systems
Continuous flow systems
Continuous flow ("instantaneous") systems have no storage capacity and heat water upon demand. They cannot "run out" of hot water like storage systems. The most economical fuel for continuous flow system is natural gas. They can also use LPG or peak rate electricity, however the running costs will be higher.
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Figure 2: Continuous flow systems
Fuel types
The most common fuels used in hot water systems are natural gas and off-peak electricity (storage units only). The following are 6 fuel types according to "Energy Smart Housing Manual":
Natural gas
Available 24 hours a day at a set rate.
Have fast recovery times and smaller storage tanks.
Can be used in storage and continuous flow systems.
All natural gas systems are rated for their energy efficiency with Energy Rating labels - The more stars, the more energy efficient.
Internal and external models are available.
LPG is used in areas where natural gas in not available. Running cost for LPF systems are 50-100% higher than natural gas.
Off-peak electricity
Heats water overnight (generally between 1 am-7 am or 11 pm-7 am) to provide adequate hot water for daily usage.
Requires larger storage capacity than gas units to serve the same size household.
Only available for storage systems of 160 liters or greater capacity-not available in continuous flow systems.
Internal and external models are available.
Your electricity supplier can inform you as to what tariff to choose. The six-hour tariff (1 am-7 am) is generally cheaper than the eight-hour tariff (11 pm-7 am).
Solar energy
Can supply 60-70% of hot water needs free in Victoria (60-65% in Melbourne).
Usually the cheapest system to run, but relatively high purchase costs makes a payback period of around ten years.
All systems have supplementary boosting to provide hot water during periods of low sunshine. Off-peak electricity, gas or solid fuel boosting is available.
Generally located on the roof, with the storage tank directly connected to solar collectors. However, the tank can be located at ground level in some systems.
Mains and constant pressure systems are available.
Peak rate electricity
Can be used for continuous flow units and storage heaters of less than 160 liters capacity.
Can be very expensive to run, and should be avoided where other options are possible.
Solid fuels (wood, briquettes, coal, etc.)
Costs can vary greatly.
Can be used alone or in conjunction with off-peak electricity and/or solar constant pressure storage units.
Unless specifically designed, cannot be used with mains pressure systems.
Heat pumps
A high-efficiency method of water heating, using around 65% less electricity than conventional water heaters.
Heat is extracted from the atmosphere using a refrigerant gas, and used to heat water in a storage tank.
Low running costs, similar to natural gas or off-peak electric systems.
Have high purchase costs.
Ventilation
ANDREW
Sub-conclusion
WTE
Water Conservation
Low water using fittings/appliances
MARK B
Rainwater capture and reuse for the roof
MARK B
Grey water recycling
MARK B
Black water recycling
MARK B
Sub-conclusion
WTE
Conclusion
WTE
