Low Energy Homes come in various forms and energy efficiency levels, currently the best dwellings are built to a standard called "passive House" standard. The Passive House concept originated in Germany in the late 1990's, its aim is to provide comfortable living conditions while ensuring greatly reduced energy consumption. Passive House design seeks to establish a "zero carbon home" though very low emission rates.
The aim of the Passive House concept is to construct a house that comes as close as possible to heating and cooling itself in a passive ultra low energy manner. As Passive Homes are super insulated the actual heating requirement is incredibly low and only required during the very coldest months of the year.This represents a massive energy saving when you consider that anything up to 75% of a typical homes energy requirement will be spent on space heating alone.
Passive housing seeks to minimise energy losses while maximising energy gains from natural and renewable resources. This is achieved in the design of the passive house by combining the principles of passive solar radiation with a highly insulated and air tight building envelope, (external perimeter)
Heat Recovery Ventilation is essential within high specification airtight buildings, this controlled mechanical ventilation of the building reduces energy consumption and allows the building to breath in a controlled and precise manner.
Based upon current fuel prices, and on a 100mtr square (1,030 ft) home, a Passive House will have an annual heating bill in the region of £80.00 to £100.00. This corresponds to a 85% saving on what you would expect to pay for heating a typical new home built to comply with the very latest building regulations and standards.
Such enormous energy savings are achieved though good design, super insulation levels, air-tightness and making the most of free heat gains from passive solar radiation that "conventional" style heating is no longer required.
The overall effect of constructing a house to Passive House standards is to greatly reduce energy consumption and thus carbon emissions, by following this path the building will achieve the very best possible energy rating, attaining an "A" grade rating on its BER certificate. Thus, making it a comfortable and affordable place to live, and adding considerable value to its sale price. Today in this era of high energy prices people are willing to initially pay a little more for high quality, well constructed low energy homes, that they know they can afford to run both today and for years to come.
To meet the high performance standards of a Passive House, the annual heating requirement in a passive home must be less than 15 Kilowatt hours per square metre of living space per year. To put this into perspective a standard house built to meet current building regulations would typically have an energy consumption of 110 KWh/mtr square per annum or more. This figure is more than seven times the Passive House standard of just 15KWh/mtr sq per annum.
The maximum annual energy input for a passive house is set at 42 KWh/msq/yr. The typical; non passive built under the 2006 regulations would be expected to have an annual total energy consumption in the region of 150 KWh/msq/yr, which is over three and half times the total energy consumed within a Passive House. It can thus be seen that Passive Houses are extremely efficient in terms of energy consumption and , assuming quality and workmanship , are capable of providing there owners with an enhanced level of comfort at less cost.
The following are the basic features that distinguish Passive House Construction.
1 - Compact form and high insulation levels
All components of the exterior shell of the house are insulated to achieve a U-value that does not exceed 0.15 W/(m2K).
2 - Southern aspect and shade considerations;
Passive use of solar energy is a significant factor in Passive House design. The elevation with the largest proportion of glazing should be orientated 30 degrees off due south. This allows for a high degree or solar radiation but avoids the direct heat of true southern orientation.
3 - Energy efficient windows glazing and frames;
Windows (glazing and frames combined) should have a U-value factor of 0.80 W/(msqK).
4 - Building envelope air tightness;
Air leakage from the building must be less than 0.6 times the house volume per hour.
5 - Passive pre-heating of fresh air;
All manner of air pre-heating is available, these include solar thermal panels, underground air warming systems or a geothermal heating system which would also proved the dwellings hot water and small amount of additional central heating.
6 - Heat recovery ventilation (HRV)
All of the buildings ventilation is controlled by the homes HRV system, 75% or more of the heat is captured and returned into the building.
7 - Hot water generation using renewable energy systems;
Domestic sanitary hot water can be provided by heat pumps, solar collectors, recycled wood pellet boiler or even electricity generated by Pv collectors.
8 - Energy saving household appliances;
The Passive Home should incorporate only low energy appliances, these would typically include a refrigerator & deep freeze, washing machine, tumble drier and ultra low energy lighting, plus low water volume sanitary fittings. Rainwater harvesting for WC flushing, washing machine usage and light irrigation would also be advisable.
Laying out of the garden should also be given consideration, if the prevailing wind is from the cold north, planting of trees and dense shrubbery will shield the building from the direct assault of the worst gales. Planting in the southern aspect must be carefully considered as shading may reduce the solar gain the building requires to operate efficiently.
If you would like more information please contact us, we will shortly be expanding this site to include low energy homes we are constructing for clients, and more details about the supply of low energy homes from factory pre-cut packages.