GREEN TERMS SIMPLIFIED
Passive Thermal Design
A design focused on natural methods of climate control to reduce the amount of greenhouse gases generated as a result of heating or cooling your home artificially. There are four primary passive solar energy configurations
Solar gain (direct, indirect, isolated)
Direct - The most common area of Solar gain is Direct Solar Gain, controlling the amount of direct solar radiation reaching the living space. The correct orientation of key living areas with suitably positioned windows and a large mass placed within the space to receive the most direct sunlight in cold weather and the least direct sunlight in
Indirect - Indirect gain directs solar radiation to areas adjacent but not part of the living space. Heat enters the building through windows or walls and is captured and stored in thermal mass, then slowly transmitted indirectly to the building through conduction and convection.
Isolated - Isolated gain involves utilising solar energy to passively move heat from or to the living space using a fluid, such as water or air by natural convection or forced convection. Heat gain can occur through a sunspace, solarium or solar closet. These areas may also be employed usefully as a greenhouse or drying cabinet.
Using the thermal mass in concrete slab floors to store heat in the winter can lower artificial heating needs.
This involves the use of insulating materials to the perimeter of a home to retain or deflect heat depending on the season. Materials that insulate well do so because they are poor conductors of heat or are able to trap air which is a poor conductor. Instead of passing heat, they form barriers between interior and exterior spaces.
Windows in a well-designed passive home serve as solar collectors, bringing in light and heat while providing ventilation. This can be controlled by the efficiency of the glass to repel heat or light, the frame material as a conductor and interior/exterior coverings for extreme times of the day.
Varying eave widths and adjustable screening to glazed windows and doors will prevent excessive heat loading in summer. Good natural ventilation can eliminate the need for air-conditioning. The positioning of vegetation or water adjacent to windows can act as a natural cooling mechanism for air passing over. Use of ceiling fans to circulate air within a room to replicate a breeze can 'almost' be called passive due to their very low running costs. Ceiling fans don't lower the temperature unlike air conditioners.
Embodied energy in Materials
The use of incorporating recycled materials where possible to avoid the impact of manufacturing new materials. It’s also important to consider the energy that is involved in processing the material ready for construction use. Aluminium for example, requires very large amounts of energy to transform it from its raw state into aluminium doors and windows. Transport of a material either to site or to distributors should also be considered, using locally produced materials can reduce the embodied energy of a home.
Rainwater harvesting has become a common practice in domestic construction with the water then used in certain areas of a home. New standards in water flow limiters to plumbing fittings have also resulted in a more conservative use of water. On-site grey water processing systems are also being designed and implimented to new housing estates.
A healthy interior is about making choices with the products and materials you use in your home when you build or renovate. In doing so, you can reduce your risk of allergies, asthma and chemical sensitivities, particularly in your children.
Materials and colours can be chosen to reflect or absorb solar thermal energy. Using information on a colour for electromagnetic radiation to determine its thermal radiation properties of reflection or absorption can assist the choices.
Chemicals & Toxins
A home built with lower chemical emitting products results in the greater long-term physical and mental health for it's occupants, especially with many people now being intolerant to a multitude of materials, chemicals and toxins. It also impacts less on the environment for the manufacturing and disposal of these products.