The finest investment in your health and your financial security

Bio-Solar-House Examples in St. Alban, Germany
Bio-Solar-House Examples in St. Alban, Germany

The Idea

At the age of 58, Klaus Becher, a mechanical engineer, wanted to build a retirement home for himself after a long working life.

He had a clear idea of what this house should be like. It should

  • be built with natural materials for the sake of the environment,
  • have a good and healthy indoor climate,
  • avoid or even exclude health risks,
  • be produced with the tiniest energy input possible,
  • require as little heating costs as possible,
  • be absolutely easy to look after,
  • cause virtually no maintenance costs,
  • keep repair costs as low as possible,
  • be easy and stress-free to build.

Without further delay, Klaus Becher began to think about how such a house could be built. He developed a new building and energy system, which took into account the experiences of housebuilding of the previous century and the laws of nature.

Based on these principles, Klaus Becher designed and built his own dream house.

It is a house which

  • protects the health of its occupants,
  • has a very long lifespan,
  • requires virtually no maintenance,
  • makes the most of solar energy,
  • helps to reduce environmental pollution.

He named this house, or rather its basic principle, “Bio-Solar-House” and had it protected by letters patent.

The Challenges of Facing House-Building Today

Saving energy

Prices for fossil fuels like oil and gas will inevitably rise as they become more scarce. The cost of heating homes will therefore become unaffordable to some people in the future.

Bio-Solar-Houses is designed to be independent of fossil fuels and to use alternative energy sources instead. This decoupling of dependency on fossil fuels is a key feature of our homes.

A healthy kind of habitation

“Your home is your castle”, your refuge, in which you feel happy and well. But an indispensable precondition is that the house you live in keeps you and your family healthy.

Nowadays allergies have become one of the most frequent types of illness. Often allergies are triggered by dust mites, mildew and various chemical substances. Bio-Solar-Houses® are therefore built in a way so as to eliminate these health hazards to the greatest possible extent.

Conserving the value of a house by protecting its basic fabric

Your house is an investment in the future. To make sure this investment keeps its value, you need a Bio-Solar- House® with its future-oriented architecture. Its building materials are ecological and fulfil the highest standards as to lifespan and endurance.

Low running costs

A Bio Solar House® is designed to be affordable to run. This means that it provides excellent energy efficiency and only uses proven low maintenance technical equipment to improve this still further.

It delivers its heat in a diffuse manner and collects free heat from the sun. Complicated technical equipment is always expensive and requires a lot of maintenance work.

Energy-Saving and Passive Houses

In order to reach this goal, new concepts of building houses had to be developed.
Such concepts were called “energy-saving” or “passive houses”. These new types of houses attain their low heating and energy costs by a combination of various techniques:

  • a high degree of heat insulation in walls, roof, windows and footing
  • avoidance of thermal bridges and making the building airtight
  • controlled ventilation with heat recovery
  • energy-efficient heating systems
  • solar collectors for hot water supply

Many of the energy-saving and passive houses offered on the market were built in this way. They do save heating energy, there are, however, disadvantages which have to be taken into account.

The disadvantages of many low-energy houses

Living in a “plastic bag” In order that the water vapour caused by any occupant in a house plus the associated odours and contaminants can escape from inside the house in a natural way, the walls of the house must be permeable to uncondensed water vapour, i.e. they must be able “to breathe”.

In the case of most low-energy and passive houses, however, this is not the case. In order to save as much energy as possible, the exterior walls of these houses are extremely well-lagged and therefore impermeable to water vapour.

Mildew and mites

The vapour therefore accumulates in the inside air where it can condensate and cause mildew formation, which endangers the health of the occupants and can destroy building materials.

And there is another risk: mites, especially dust mites proliferating particularly well in a warm and damp atmosphere. Their droppings contain allergy causing substances, which spread out as dust in the house where they are breathed in by its occupants and often cause dust allergy.

“Artificial Respiration”

To avoid mould formation, the damp interior air must be replaced by dry fresh air from the outside. This is why, above all in passive houses, ventilation systems with waste heat recovery are installed.

However, this equipment is expensive, requires a lot of maintenance work and consumes extra electrical energy. Moreover, these systems are potentially dangerous to people’s health, since in an improperly fitted heat exchanger legionella can grow. These can escape into the interior air and cause life-threatening legionnaires’ disease among the occupants of the house.

Caution: Filter!

The filters in the ventilation system serve as a means of cleaning the exterior air from pollutants, pollen and dust. In these very filters and air channels, however, bacteria can multiply, if they are not regularly and properly cleaned. The bacteria can get into the interior air and cause illnesses among house occupants.

The Much Acclaimed Building Principle of the Bio-Solar-House

Special features of the Bio-Solar-House

The Bio-Solar-House is built in such a way that the disadvantages of many low-energy houses are avoided by the principles of its design.

Bio-Solar-Houses belong to a new generation of low carbon houses whose primary energy requirement is way below the levels set by law for new houses in the UK and Germany. Moreover, Bio-Solar-Houses set completely new standards with regard to ecological and health-related methods of building houses.

This is why the construction and energy concepts of the Bio-Solar-House® have won a considerable number of awards, among them

  • 1st prize for Germany’s house with the healthiest living conditions
  • Prize for Innovation 2000
  • Special Prize of Solar ’99
  • Environmental Prize of the State of Rhineland-Palatinate
  • Energy-Plus Certificate
    and many more.

The Bio-Solar-House is a bio-passive house

Our houses are incredibly energy efficient, but this has not come at the expense of the occupants’ health. Our bio-passive design and principles combine to provide large cost savings whilst creating a healthy internal environment that is also environmentally sensitive.

The Bio-Solar-House® therefore takes the aims of the passive house movement and enhances it to create a whole new generation of buildings. So how have we achieved this?

The house-in-a-house principle

The well-insulated inner house and the air cushion between the exterior and the interior house are heated by the transparent surfaces of the outer house and the conservatory by means of the greenhouse effect of daylight.

The materials of the warm inner house cladding allow the uncondensed water vapour generated in any house to diffuse into the airspace between the inner and the outer house. Thus any damage to the building fabric caused by humidity and harmful mould is made impossible.

Since the non-condensed water-vapour is a gas and has only half the weight of air, it can escape, because of its natural draft, up to the roof and into the outer air without any mechanical support.

The outer house keeps the effects of the weather at bay and shields the inner house like an overcoat.

Building the houses of tomorrow

Bio-Solar-Houses are very efficient energy- saving houses. Their demand of heating energy is between 10 and 25 kWh p.a. per sq. m floor space and their primary energy requirement is less than 10 kWh per sq. m per year.

For this reason Bio-Solar-Houses are the absolute frontrunners in the race for the development of houses of high energy-efficiency.

This is why Bio-Solar-Houses are subsidised by “Umweltbank”, a German ecology bank, through credits at preferential rates.


Ingeniously simple!

The house-in-a-house principle makes it possible for the water vapour caused inside the house to rise and get outside without heat loss or expensive ventilation systems.


Whoever builds a house today should take into account the technological and ecological development of the next 20 or 30 years. Whoever fails to do this, will invest in real estate that will not provide sustained value for its owner.

Bio-Solar-House® is a house for the future, built today. To reflect this we use the motto ‘Build your own future’. It has been designed to have a low carbon footprint both in its construction phase and throughout its life. Natural materials act as a carbon sink and the low demands on heating mean that it is easier to achieve a ‘One Planet Living’ lifestyle.

Say goodbye to oil and gas bills

Bio-Solar-Houses require neither oil nor gas and therefore they are independent of price developments on the energy markets.

The energy needed for heating and hot water is mainly provided by the sun in the summer, and this is free of charge. Additionally solar energy is absorbed by a collector placed under the part of the roof which is glazed. This energy is stored in a maintenance-free thermal water store.

Hot water needed for showering, bathing and washing dishes is heated via a heat exchanger in a flowtype thermal store and is therefore free of legionella.

In the winter and when there is not enough sunshine, a wood-burning stove is used as an additional energy provider substituting the insufficient sunshine.

Bio-Solar-Houses do not require oil or gas and are therefore largely independent of the volatile and increasing prices associated with these fossil fuels.

Additional free energy from the sun

As well as the free hot water provided, you could also specify photovoltaic panels for your home. Solar PV panels can help to reduce your annual electrical needs //and attract the Feed In Tariff that helps to cover the initial outlay for the system.

Natural building materials

Our philosophy for reducing carbon and creating long lasting and healthy environments in houses means that Bio-Solar-Houses are made of a range of natural, recycled, recyclable and renewable materials. Wood is the primary material used and this acts as a carbon sink as well as being a material open to water vapour diffusion. Our insulation products of choice are recycled newspaper and wood fibre board and the frame can be either wood or metal. Furthermore, the building materials are not treated with chemicals and therefore do not emit harmful substances into the environment.

A healthy atmosphere of well-being

As the walls of Bio-Solar-Houses are open to water vapour movement, excessive humidity cannot accumulate in the internal air of the house. This means that the moisture in the house is kept at a low level ensuring that mould and mites have no chance to develop.

No complex technological fixes

Bio-Solar-Houses are designed to make use of the natural laws, so there is no need for complex ventilation systems that need regular maintenance. Bio-Solar-Houses® do this for you naturally. This eliminates any risks associated with mechanical failure or the potential build-up of bacteria or legionella.

Pleasant radiant heat

When heating is required in the home Bio-Solar-Houses deliver this via radiant wall heating. This is similar to underfloor heating but has the added advantage that it does not cause dust to rise up from the floor, thus maintaining a healthier and cleaner internal environment. Another advantage of radiant wall heating is that the temperature is perceived to be higher than it actually is. This gives the house a cosy and comfortable feel and also means that less heating is actually required.

Romantic fireplace in the conservatory

When the weather is cold and overcast the amount of solar energy may not be sufficient for the home, so in Bio- Solar-Houses we install beautiful biomass boilers. These boilers look great, provide a lovely atmosphere in the building as well as providing the warmth for the radiant wall heating and hot water needs of the family.

Cool in the summer

The inner house is low in thermal mass and highly insulated so does not absorb lots of the summer heat. The outer house is well ventilated and hence disperses any excess heat from solar gains. The conservatory is also able to be shaded, thus allowing the rest of the house to remain light and bright. Doors and windows in the inner house can also be opened at night to air the home even more.

The Building and Energy System of the Bio-Solar-House

Best Available Building Standard

The building and energy system on which the Bio-Solar-House is based is a pioneering standard for several reasons. Its cost-effectiveness, its energy efficiency and its sustainability as to the use of wood as a natural and renewable building material allow the construction of long-lasting residential and functional buildings, which have a protective influence on the health of their occupants, the environment and on our climate.

Thanks to its design as a “house in a house”, the building and energy system of the Bio-Solar- House is substantially more efficient than the passive house standard.

Free of harmful substances and dust The Bio-Solar-House has not an artificial but a natural indoor climate achieved by the facts that it can be kept free of harmful substances and that the raising of dust is avoided by its radiant wall heating. The natural way of living of its occupants is not impaired by artificial ventilation systems.

Warm in the winter, cool in the summer

Its rooms are cosy and warm in the winter and cool and comfortable in the summer. As to size, form, look and cardinal points there are no restrictions.

More efficient than the passive house standard

A Bio-Solar-House requires

  • up to 15% lower building costs
  • up to 80 % less heating and operating costs
  • up to 90% less primary energy
  • no vapour barrier
  • no mechanical ventilation system
  • no fossil fuel heating energy
  • no six monthly filter changes

and it reduces the environmental burden by producing
over 90% less CO2