A ultra-low energy house is a house built using low energy methods, and allows a very low and very efficient use of energy. Several types of ultra-low energy houses exist. A energy-neutral or energy-positive house is even more energy efficient, the latter even producing more energy than it consumes.
General design
Ultra-low energy houses are generally sited so as to create as little of a negative impact on the surrounding ecosystemW as possible, oriented to the sun so that it creates the best possible microclimate (typically, the long axis of the house or building should be oriented east-west), and provide natural shading or wind barriers where and when needed, among many other considerations. The design of a sustainable shelter affords the options it has later (ie: using passive solar lighting and heating, creating temperature buffer zones by adding porches, deep overhangs to help create favorable microclimates, etc).[1][2] Sustainably constructed houses involve environmentally-friendly management of waste building materials such as recycling and composting, use non-toxic and renewable, recycled, reclaimed, or low-impact production materials that have been created and treated in a sustainable fashion (such as using organic or water-based finishes), use as much locally available materials and tools as possible so as to reduce the need for transportation, and use low-impact production methods (methods that minimize effects on the environment).[3][4]
Special types
Passive solar house
A passive solar house is a ultra-low energy house that achieves this low energy use (or even energy-neutrality) by means of large, well-insulated windows (that let in large amounts of sunlight, heating the building at cold days; windows can be covered at hot days), very rigourous insulation, airtightness and efficient ventilation[5].
It does differentiates from regular energy-neutral/energy-positive houses in that it doesn't simply add sufficient power sources (ie PV-panels, wind turbines, ...) to level out the energy use, but focuses primarily on energy conservation instead.
The basic requirement for passive solar heating is that the solar collectors must face the prevailing sunlight (south in the northern hemisphere, north in the southern hemisphere), and the building must incorporate thermal mass to keep it warm in the night.
A recent, somewhat experimental solar heating system is called "Annualized geo solar heating". It is practical even in regions that get little or no sunlight in winter.[6] It uses the ground beneath a building for thermal mass. Precipitation can carry away the heat, so the ground is shielded with 6m-long skirts of plastic insulation. The thermal mass of this system is sufficiently inexpensive and large that it can store enough summer heat to warm a building for the whole winter, and enough winter cold to cool the building in summer. The sloped water-tight skirts of insulation extend upto 6m from the foundations for the purpose of preventing heat leakage between the earth used as thermal mass, and the surface.
In annualized geo solar systems, the solar collector is often separate from (and hotter or colder than) the living space. The building may actually be constructed from insulation, for example, straw-bale construction. Some buildings have been aerodynamically designed so that convection via ducts and interior spaces eliminates any need for electric fans.
A more modest "daily solar" design is very practical. For example, for about a 15% premium in building costs, the Passivhaus building codes in Europe use high performance insulating windows, R-30 insulation, HRV ventilation, and a small thermal mass. With modest changes in the building's position, modern krypton- or argon-insulated windows permit normal-looking windows to provide passive solar heat without compromising insulation or structural strength. If a small heater is available for the coldest nights, a slab or basement cistern can inexpensively provide the required thermal mass. Passivhaus building codes in particular bring unusually good interior air quality, because the buildings change the air several times per hour, passing it though a heat exchanger to keep heat inside.
In all systems, a small supplementary heater increases personal security and reduces lifestyle impacts for a small reduction of autonomy. The two most popular heaters for ultra-high-efficiency houses are a small heat pump, which also provides air-conditioning, or a central hydronic (radiator) air heater with water recirculating from the water heater. Passivhaus designs usually integrate the heater with the ventilation system.
Aerodynamics of the house
Rounded, aerodynamic buildings also lose less heat.
References
External links
- ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namedReferenceA - ↑ Hamilton, Andy, and Dave Hamilton. The Self-sufficient-ish Bible: an Eco-living Guide for the 21st Century. London: Hodder & Stoughton, 2009. Print.
- ↑ Snell, Clarke, and Tim Callahan. Building Green: a Complete How-to Guide to Alternative Building Methods : Earth Plaster, Straw Bale, Cordwood, Cob, Living Roofs. New York: Lark, 2005. Print.
- ↑ Hamilton, Andy, and Dave Hamilton. The Self-sufficient-ish Bible: an Eco-living Guide for the 21st Century. London: Hodder & Stoughton, 2009. Print.
- ↑ http://en.wikipedia.org/wiki/Passive_house
- ↑ Stephens, Don. September 2005. "'Annualized Geo-Solar Heating' as a Sustainable Residential-scale Solution for Temperate Climates iwht Less than Ideal Daily Heating Season Solar Availability." ("Requested Paper for the Global Sustainable Building Conference 2005, Tokyo, Japan"). Greenershelter.org website. Retrieved on 2007-09-16.