Daylight - through the use of sufficient windows to avoid the use of electric lighting during the day
Passive cooling - Intelligent orientation to take advantage of convection currents, cooling breezes and sunlight.
Passive Solar Heating - to warm a building in the winter; with due care to provide shade insummer and thereby prevent overheating.
Thermal mass stores - normalizing temperature by storing heat during the day, releasing it at night. This can be designed to heat the building in winter, and cool it in summer
Insulation - well-insulated windows, doors, and ceilings and walls to help reduce energy loss.

Every one of the above elements contributes to reducing energy usage, without excessive construction cost or intrusion.

Heating and cooling systems account for a significant percentage of energy used in buildings. An energy efficient home optimizes heating and cooling systems that utilize either passive solar heating or active solar heating technology.

Passive heating is relatively inexpensive, any additional cost being quickly recouped through energy savings. Active heating technologies can be relatively expensive and can add significantly to the projects cost. With a well integrated sustainable design concept, a building can employ a combination of passive and active solar heating at acceptable cost.

Substantial energy and financial savings can be gained from:

Downsized heating, ventilation and air-conditioning (HVAC) equipment
Hot water heat recycling is used to reduce energy usage for domestic water heating.
Ground source heat pumps are more energy efficient then other forms of heating and cooling.
Onsite generation of renewable energy from solar power, wind power, hydro power, or biomass.

Cost of Sustainable Heating Systems

Onsite power generation is the most expensive feature to add to a building. Other technologies can be incorporated at little addtional cost. The cost of incorporating passive solar heating can be reduced through:

The design of the building
The materials used
The use of passive solar elements
External shading
Thermal mass
Good insulation
Heat reclaim systems
Night cooling - using cool night air to pre-cool the building’s thermal mass.
Heat pumps - a very efficient way of transferring heat or cooling from free air, water or ground to the building.
Smart selection of high efficiency and variable speed fans and pumps.

Special Considerations

Certain systems and materials that benefit the energy efficiency of a home, have a dark side:

Certain mechanical heating and cooling systems use refrigerants - potent greenhouses gases damaging to the ozone layer. Only use refrigerants with a zero Ozone Depletion Potential (ODP) and a Global Warming Potential (GWP) of less than 10.
Thermal insulation of pipe work and ducting must be CFC and HCFC
Heating systems often use gas and electricity - which rely on the use of fossil fuels, known to be in limited, exhaustible worldwide supply.

Types of Sustainable Heating Systems

There are number of affordable, sustainable heating systems, including:

Hot Water Heat Recycling / Drain Water Heat Recovery
Solar Heating
Wood Pellet Stoves
Ground Source Heat Pumps (GSHP)

Hot Water Heat Recycling

Water typically enters the home between 5-12ºC. It is then heated to 50ºC in the hot water tank, and mixed with cold water to provide a shower head temperature of around 41ºC. Water from the shower is then flushed down the drain at 37ºC.

Hot water heat recycling uses heat exchanger technology to recover and reuse hot water heat from various activities such as dishwashing, clothes washing and especially showers. The technology is used to reduce primary energy consumption for domestic water heating while also reducing greenhouse gases. Standard units save up to 60% of the heat energy that is otherwise lost down the drain when using the shower.

Hot water heat recycling is also known as drain water heat recovery, greywater heat recovery, and shower water heat recovery.

Drain Water Heat Recovery - works well in conjunction with other types of water heaters, especially demand and solar water heaters.

Recycling this heat back into your homesubstantially reduces hot water heating costs.

More on Sustainable Water Management

Solar Heating

There are two types of solar panel heating systems, which are based on different technologies.

Solar Water Heating systems [Solar Thermal Systems] uses the suns energy to heat water.
Solar Photovoltaic or Solar PV systems generate electricity - is an expensive technology, with a long payback period. Since it also requires connection to an electrical system to boost power, storage of power within this system is not yet fully developed. In many countries, the heat from the sun is insufficient year round to provide continuous power. For this reason, photovoltaic systems must be combined with another power source, making the entire energy supply set up prohibitively expensive for the average home.

More on Passive Solar Heating

More on Active Solar Technology

Wood Pellet Stoves

Wood Pellet stoves use softwood pellets typically made from manufactured wood by-products, such as sawdust. Burning wood is not one of my favorite heating forms, as the emissions frm chemically complex non-softwood pellets is untested, and can potentially have environmental and health hazards.

Ground Source Heat Pumps [GSHP]

Ground Source Heat Pump systems use a high-quality ground loop and heat pump system to collect solar heat stored within the ground, and convert it to energy. They then store this energy for future use. These systems are currently expensive to install, and are not able to supply the total heating energy needs of a home. Typcially they provide only a maximum of 70% of the required heating energy.

The most acceptable sustainable heating system for an environmentally-friendly home is generally a combination of the systems above. Many countries provide grants or tax incentives, which help to offset some of the installation cost.

Next: Active Solar Heating

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