Low Energy Houses

  • The Importance of Air Tightness

    The heating of our homes and the cooling of our offices usually accounts for a very significant proportion of the buildings energy consumption. The main causes of energy inefficiency and waste are generally related to inadequate insulation and excessive air leakage. With such vast amounts of energy used within the community to ensure that our office buildings and homes have pleasant and comfortable conditions, it makes sense that we should conserve as much of it as possible. Heat or coolth, being blown away by poorly insulated and draughty buildings is an ecological disaster and grossly inefficient, let alone expensive.

    Energy conserved through the use of good quality insulation, especially recycled insulation materials such as Warmcell, that far outweigh the energy used to manufacture it, provide for much more comfortable conditions, and save money year on year. Further information on insulation materials is available under the Low Energy Homes section of our web site.

    However, did you know, you can have the very highest levels of insulation, and the worst heat losses?. 

    For insulation to be effective, draughts and the ingress of uncontrolled air though poor construction need to be addressed. Poor air tightness significantly effects the performance of insulation materials. Poor quality workmanship, lack of attention to detail and incorrect draught proofing details have a massive effect upon the buildings final efficiency, and once constructed, are hard to locate, without the correct equipment (see our Thermograpy Section on this web site) and extremely difficult to rectify.

    The answer is quite simple, construction air testing, we are able to offer a services where we pressure test the building, most importantly, during the construction process to evaluate the air tightness of the structure. Any defects can be located with the aid of the thermal imaging camera and defects repaired before its to late in the build process. Such testing is now mandatory in many European countries.

    To maintain the energy efficiency predicted at the design stage of a new building, requires stringent quality checks and supervision by the clients design team, penetration of the buildings insulated shell should be kept to an absolute minimum, every hole is a potential weakness to the airtight envelope. Where it is essential for services to pass through the external envelope special rubber grommets are used to stretch and seal against the walls of pipes and cables thus maintaining the airtight barrier.

    All exterior openings for doors and windows require a draft proofed seal bonded to the external airtight membrane, this is easily undertaken and special high quality adhesive tapes are used to ensure a quality airtight finish.

    For more details about airtightness and low energy homes in general, please consult the Low Energy Homes section of this web site.

    If you have a problem with a building and require assistance please contact us.

  • Low Energy Timber Frame Homes

    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.

  • Heat Recovery Ventilation

    We are all aware that in order to construct an environmentally friendly, economical and comfortable home we need to ensure the structure is draft free and adequately insulated, so as to conserve heat and reduce energy consumption and running costs. In order to avoid the building becoming stuffy and unhealthy, stale air needs to be removed and replaced with fresh air.

    In the old days, we simply flung open the windows, and all the fresh air flooded in, as the heat escaped at the same time. Today, we are all more environmentally conscious and with escalating fuel costs are far from keen to let our precious expensive heat escape.

    So, the dilemma, ventilate the house, without losing all the heat. Heat Recovery Ventilation is the answer, its simple, inexpensive and highly efficient.

    The Heat Recovery solution is rather simple, transfer the heat being expelled from the stale air to the incoming fresh air during the ventilation process. So, how is it done? The HRV unit, in its simplest form is a metal box with a air to air heat exchanger and two fans inside. One extract fan draws stale air out of the bathrooms, cloakroom and kitchen through a network of small ducts, while the other fan draws in fresh outside air from outside. At the HRV unit, the warm stale air passes over the heat exchanger giving up its heat to the cooler incoming fresh air. The newly warmed fresh air is then introduced into the building, and the newly cooled stale air exits the building via a grill in the outside wall. Its that simple.


    I Only Have One Large Room What can i do?

    For studio flats or single room applications, we have a range or smaller HRV fans that mount directly into the wall or into the ceiling. They work on the same principle. With twin fans and a small heat exchanger, these units very effective and can prove very useful for ground floor applications where it may not be safe to leave windows or doors open during periods of non occupancy.

    What Happens if it's Really Cold Outside?

    Most domestic and commercial HRV units, excluding the smaller wall mounted model have an inbuilt electrical re-heater battery and an air sensor, if the air is to cold entering the building the re-heater battery / element warms it to an acceptable level before introducing it into the building.

    So What are the Benefits of HRV;

    1 - Reduces heating costs

    2 - Clean fresh air benefits everybody and the building fabric at the same time.

    3 - Greater security with closed windows and no unpleasant draughts.

    4 - Greatly reduces the build-up of condensation and black spot mould growth on walls.

    5 - Allows the building to remain ventilated during vacations and periods of non occupancy. 

    We have a large and varied range of HRV units and HRV fans available for any type or size of project, from domestic studios to large commercial applications.

    Tell me More About The Installation Process

    The installation process is as stated relatively simple, and can be undertaken my any competent person. However, the design, setting to work, and commissioning is a more complex matter, and is specialist work requiring specialist air measurement equipment. We at the Low Carbon Company Limited can undertake this for you at very competitive rates.

    Within an efficient system, the pre-heated incoming fresh air entering the dwelling is no more than two or three degrees cooler than the internal room temperatures of the room its entering. As outlined previously, the basic heat exchange principle is simple, and the design and operation totally effective. However, incorrectly designed and dimensioned systems can cause increased energy consumption, high fuel bills, drafts and very uncomfortable living conditions.

    To ensure maximum energy efficiency and fuel cost savings, the whole installation needs to be professionally designed and supplied by specialist, we are here to fulfill that roll. We understand the "whole energy picture" unlike many small contractors whom only concentrate on there respective field, we are not limited in this manner an can overview the complete mechanical package, designing and supplying the correct products that work seamlessly together but are installed by the individual tradespeople.

    Very often on building projects, the plumber does not talk to the electrician, who does not talk to the heating engineer, and nobody asks the client about what there expectations are, we can view the "overall scheme" and design a system that meets with the clients criteria and budget.


    Well designed HRV systems are easily capable of retaining 75% of previously lost energy through exhaust ventilation. The fresh air can be treated and filtered for pollen, dust and even noise pollution in extreme circumstances. If required, we can design more sophisticated installations, which may incorporate more advanced features such as automatic humidity sensors that increase the ventilation rate as humidity rates build-up within bathrooms or shower room. Night set-back and vacation mode settings or interconnection with "BEMS" controls can also be offered to further fine tune the system and reduce energy.

    Before considering any HRV system, the building in question needs to be well insulated and as draft free as possible. Otherwise the energy savings anticipated will never be achieved. Once a suitable outline design has been provisionally selected,that fulfills the clients requirements and is in harmony with the buildings mechanical services, the HRV system must be fine tuned and matched to the individual building in question. This requires many factors to be considered and include calculations to attain the volume of the building, occupancy levels, heat gains and lighting loads all need to be calculated, to establish the ventilation rate (amount of air to be ventilated) and consequently the size and requirement for the fresh air intake duct-work and external louvre dimension, and overall system requirement.

    As an indication of the likely cost  for a basic domestic system which includes the design work, supply, installation and commissioning of a HRV system for an average size 3 bedroom home is in the region of  £5800.00 fully installed, certified and tested. If we are working on a design and supply only basis the cost is somewhat lower.

    For more information, or a quotation / project budget costing, email your project drawings to us in jpeg format and we will be pleased to forward costs.

  • Geo-floor Underfloor Heating

    Geo-floor is a bespoke warm water underfloor heating system pioneered and developed by ourselfs, drawing from over 35 years experience in heating design, and working with some of the largest manufacturers such as Rehau and Wirsbo we have optimised the principles of ufh technology and produced a highly effective cost efficient system which can both heat and cool.

    Geo-floor is extremely versitile and cost efficient in operation, especially when operated in conjunction with either Ground or Air Source Heat Pumps. With its flexible design approach, it can accommodate any type or style of floor construction and finish.

    Geo-floor is a available to both domestic and commercial clients, and can also include various types of high grade floor insulation and screed finish if required. Incorporation of the very latest hi-tech insulation, and the systems naturally slim pipe diameter, reduces the loss of ceiling height so typically a problem within standard floor warming systems, and always a major concern to any building designer in re-furbishment or retrofit installations.

    With its unique design, the "Geo-floor lite" system can be installed into a replacement floor thickness of less than 65mm in overall depth, typically the depth of a normal floor screed. Its use of high quality multilayer insulation offers the end user a quality heating system with excellent insulation properties when ceiling height saving are at a premium.

    "Geo-floor frame"
    is a design for installation into modular or timber frame buildings, the installation allows for fast track building construction without the normal delays associated with the installation of conventional heating systems into the upper joisted floors of timber buildings.

    When matched with a Ground or Air Source Heat Pump, Geo-floor heating offers further efficiency savings over more basic installations that are typically connected to a convention fossil fuel boiler. Standard heating boilers cannot easily operate at the low temperatures demanded of underfloor installations, to operate without sustaining damage, they require complicated and expensive mechanical temperature mixing valves and pumps, to lower the water temperature to the heating, but avoiding low temperature within the boiler that can cause back-end corrosion which can seriously effect the boilers life.

    As the water temperature required to operate the system and keep the building at optimum temperature is accurately controlled by the heat pumps weather compensator system, less complicated controls and field wiring are required making the installation process fast and cost efficient.

    If you require more information or a project costing please contact us.

  • Warmcell Thermal Insulation

    Warmcell, is a cellulose insulation material and a superb way in which to use a recycled product to insulate your building. Manufactured from old and recycled shredded newspapers and cardboard, it is treated to make it fire resistant and vermin proof.

    Its application is almost limitless, it can be loose laid into lofts, blown between floor joists, sprayed onto internal cavities and compacted into the external walls of "low energy homes".

    Cellulose is a totally recycled product and in itself is recyclable if kept dry, in thus is has low embodied energy, is a non irritant, is clean and easy to install, and is totally safe for asthmatics.

    New "low energy homes" that have 300mm or more of Warmcell blown into the floors, walls and roofs have proven to be some of the most well insulated and energy efficient buildings currently available in the country.

    With its ease of installation, Warmcell can be blown into tight spaces and awkward corners more often than not overlooked in traditional glass mineral wool installations.

    The cellulose product is biodegradable and can eventually if nessary be accepted by landfill sites.

    Warmcell is usually installed by a local Warmcell agent as he has the appropriate vacuum blower kit and tools required for those tight spaces, however, it can be installed as loose infill by the DIY enthusiast.

    In the Channel Islands the local Warmcell agent is Ken Howard 07797 718 987.

  • Sheep’s Wool Thermal Insulation

    Sheep's Wool is a renewable and totally natural form of insulation. After all, we have woven clothing from wool for thousands of years, why not insulate our homes and office building with it as well?

    Sheep's wool, provided it is not imported from long distances, has a very low level of embodied energy, since unlike many other insulation materials it is a natural product manufactured without any input energy, and is processed with only minimal energy consumption.

    The ability of wool to rapidly absorbs and release water vapour (up to 40% of its weight) without any loss of efficiency, makes it a partially effective natural home insulation material, keeping buildings cool in summer and warm in winter.

    Sheep's wool has thermal conductivity of between 0.037 W/mK - 0.040 W/mK.

    Sheep's wool not only has exemplary insulation qualities and is on par with the best manufactured products, it is safe to handle, omits no gasses or fumes or irritable mineral fibres so common with glass wool styled products.


    Hemp is another renewable low embodied energy insulation material. Since 1996 the cultivation of low-narcotic hemp has been permitted in some parts of Europe, mainly Holland and Germany. As hemp production is rather limited the cost of it can be prohibitive if only relatively small areas of insulation are required.

    During hemps growth it assists in cleaning the air and reducing envioromental potution as it absorbs and decomposes carbon dioxide (C02) from the atmosphere.

    Hemp's insulation properties are similar to that of sheep's wool. Hemp has a high natural content and is recyclable and totally biodegradable in content. It is also a natural insect repellent, however for it to meet safety standards for building construction it does have chemicals added to retard fire.

    If you reqire any further information or a quotation please contact us. 

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