An Eco-house (or Eco-home) is an environmentally low-impact home designed and built using materials and technology that reduces its carbon footprint and lowers its energy needs. Eco-homes are measured in multiple ways meeting sustainability needs such as water conservation, reducing wastes through reusing and recycling materials, controlling pollution to limit global warming, energy generation and conservation, and decreasing CO2 emissions.
An Eco-house could include some or all of the following: Higher than normal levels of thermal insulation Better than normal air-tightness Good levels of daylight Passive solar orientation — glazing oriented south for light and heat Thermal mass to absorb that solar heat Minimum north-facing glazing — to reduce heat loss Mechanical ventilation with heat recovery (MVHR) system Heating from renewable resources (such as solar, heat pump or biomass) Photovoltaic panels, small wind turbine or electricity from a 'green' supplier Natural materials — avoidance of PVCu and other plastics Rainwater harvesting Grey-water collection Composting toilet Glass that has two or three layers with a vacuum in between to prevent heat loss (double or triple-glazed windows) Solar panels or wind turbines Geothermal heating and growing plants on the roof to regulate temperature, quiet the house, and produce oxygen A vegetable patch outside the house for some food
Building concepts
Energy loss
Buildings use up enormous amounts of energy. Home energy as well contributes to global warming. According to The Energy Information Administration, home energy contributes to 21% of all greenhouse gases in the United States alone. In construction as well, 48% of greenhouse gases is emitted. Some calculations make it as much as 70% of all the energy used when all the factors are taken into account. This energy is mainly for heating and lighting and therefore the aim is to design houses that are well insulated and make the best use of natural light.
Insulation
Increasing the amount of thermal insulation is the main component of preventing energy loss. According to the EPA Office of Air and Radiation, indoor air is more polluted than outdoor air, and is in the top five human health risks. Such pollution could be caused by toxic chemicals and mold and could lead to asthma induced illnesses. Insulation in Eco-homes include draft exclusion, glazing, wall, roof insulation, and other nontoxic materials. By installing insulation not only are you paying less money for heating bills, but you are also reducing exposure to toxic materials such as the carcinogen formaldehyde found in manufactured wood.
Passive solar gain
In the northern hemisphere, a south-facing site will be a much better location than a north facing site because of access to sunlight and protection from the cold northerly wind. An eco-house starts life facing the Sun.
Ideally, the site for the house should have a south westerly aspect and be protected from the north and east. It is not always possible to do this but there will usually be an opportunity to take advantage of the passive solar gain by having more glazing on either the front or the back of the building. Planting trees and creating windbreaks on the north and east sides of the site can enhanced the solar gain effect by protecting the house from the cold north easterly winds.
Having faced the house towards the Sun, high performance windows are used to draw in as much light and warmth as possible. Sunlight then floods into the house and any heat generated is retained by a highly insulated building shell, draught proof windows and doors and thermal mass within the building.
Active solar gain
Orientation towards the Sun also means that active solar systems can be fitted, both solar water heating panels and electricity generating solar panels on the roofs, further adding to the free heat and electricity gained from the sun.
Living gain
Living in the house also generates heat. Active human beings can produce as much heat as a one bar electric fire. Add to this heat from cooking, washing, lights etc. and you can begin to see how an eco-house could get too hot. Conventionally opening the windows reduces heat, but an eco-house design could include heat recovery ventilation systems.