Principles of construction

The Brikawood Passive Building rests on a concept of very low consumption construction, based on the use of “passive” heat supplied by the sun, on very strong insulation (walls, windows, etc.), on the absence of thermal bridges, on very efficient air-tightness as well as on ventilation control.

Passive homes built with Brikawood wooden bricks consume 90 % less energy for heating than an existing construction. It also consumes 50 % less than a newly-built house built in accordance with the current thermal regulation (RT 2012). Whatever it’s method of construction and it’s geographical location, a passive Brikawood home with all existing comforts does not need more than 15kWh per m² per year (that being 1,5 litres per m² and per year in petrol equivalent) in heating.

The existing Brikawood constructions show that this definition is valid for harsh climatic regions as well as southern climates; corresponding to the entire zone between France, Norway and the Reunion Islands, Canada or the Pacific area.

A passive home only costs between 10 to 20 euros a month in heating. This is far less than a low energy home (between 40 to 65 kWh (m²/a), depending on the climatic zone).  Yet its comfort is far better !

In order to warm itself, the passive home uses all sources of heat available (sun, inhabitants, household appliances, etc.) The extremely efficient insulation of the outer walls, the roof and the floor, as well as the double or triple glazed windows keep the heat inside. Fresh air is supplied by controlled double flow mechanical ventilation (VMC), inaudible (25db), which recovers the heat from the outgoing air to heat up the incoming air.

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There were four requirements  which determined whether a Brikawood building could obtain the «Batiment Passif / Passivhaus » label :

  • Heating requirements < 15 kWh/(m²/a) or heating power < 10 W/m²
  • Total primary energy requirements (household appliances included) < 120 kWh/(m²/a)
  • Insulation cover impermeability : n50 ≤ 0,6 h-1
  • Less than 10 % of annual overheating hours (>25°C)

To ensure comfort as much in summer as in winter, the Brikawood passive house was designed to avoid uncontrolled loss (known as «parasites ») especially heat loss. In this respect, it’s air-tightness is essential. The Brikawood passive house does not like thermal bridges either ; those points in the construction from which heat is lost more quickly … and needlessly. They are usually due to the assembly of the weight-bearing components of the building not being air-tight. The Brikawood passive house has drastically reduced these heat loss zones.

Technically, a Brikawood building is : a reinforced insulation, « hot » glazed windows, a heat recovery ventilation system, air-tightness, elimination of thermal bridges, optimisation of free solar supplies as well as the use of low energy appliances. Financially, the Brikawood house is the best construction compromise between  global exploitation costs and investment.

This is achieved through a particularly meticulous design and construction, of which these are the corner stones. They are not  standard obligations, but rather pieces of advice which must help to comply with the three criteria cited above : A pleasant indoor climate is possible without a heating or air-conditioning system. To achieve this, the heating requirements should not exceed the value of 15 kWh/(m²/a).

The comfort criteria should be respected in all the rooms of the house, in summer as in winter. This usually implies the following conditions :

  • The U value (thermal waste coefficient) should be inferior to 0,15W/(m²K) for the opaque partitions; double thickness Panelling with wood shaving padding
  • The U value of the windows and other translucide partitions should be inferior to 0,8 W/(m²K)

The translucide partitions (windows etc.) facing east or west (±50°) as well as those with an inclination inferior to 75 ° (compared to horizontal) must not represent more than 15 % of the habitable surface. Otherwise, they should be equipped with a temporary solar protection (shutter, curtain) with a 75 % protection factor. For the south-facing windows, the limit is fixed at 25 % of the habitable area.

  • The air temperature at the entrance of a room must not go below 17°C ;
  • The air circulation in all the rooms must not vary (ventilation efficiency) ;
  • Above all, the ventilation must respect air hygiene (DIN 1946) ;
  • The noise produced by the ventilation system must be very low (inferior to 25bDa) ;

The houses must have at least one outward ventilation vent in each room ; ventilation of the house thanks to outside air must be possible during summer nights (« summer cooling »).

The necessary primary energy for all household activities (heating, hot water, electricity) must not go above 120 kWh/(m²/a).

The principles to be respected in passive house constructions :

  • Good heat protection and density : the exterior U coating must rigorously be below 0,15 W/(m²K) ;
  • South-facing without thermal bridges and no shade : use of passive solar ;
  • Ultra-efficient glazing and window frames ; UW must rigorously be below 0,8 W/(m²K) g factor around 50 % ;
  • Air-tight : n50 rigorously below  0,6 h-1 ;
  • Heat recovery from the outgoing air : recovery rate rigorously above 75 % ;
  • Low-energy household appliances : highly efficient equipment (Energy class type A) ;
  • Passive air heating : optional : geothermics, air temperature in winter above 5°C ;
  • Total primary energy consumption (i.e. Heating, hot water, lighting and electrical appliances) below 100kWh per m² and per year ;
  • Renewable energy production to cover the house’s energy requirements (passive balance) or to exceed them (positive balance).  This for a house built with the BRIKAWOOD system.

The energy produced thanks to the installation of photovoltaic solar pannels, a wood burner or thermodynamic water heaters is used to compensate for the requirements of the household, or to re-inject it into the local or national energy grid in case of surplus.

Characteristic to Brikawood, certified due to its rigour in calculation specific to the Passiv Hauss Institut, who due to it’s ambition, was able to « take into account energy production by the building itself » and to evaluate « it’s interaction with the existing surrounding energy networks. These networks will be designed for the long term depending on their capacity to produce energy, to store it and to interact with the building ». This approach is therefore very realistical and leaves no room for approximation !

The Brikawood Home, Passive Plus, respects the passive standard criteria « generate less than 60 kWh/(m²/a) of energy with respect to the ground coverage of the building ». The Brikawood constructions are close to the Passive Premium critera as they respect the passive standard criteria and very soon « they should generate less than 120kWh/(m²/a) of energy with respect to the ground coverage of the building », that is, double that of it’s Passive Plus Home.

 

Wooden wall Heat loss coefficient

Thermal U (W/(m2.K)

Thermal phase difference

(hours)

Thickness 25 cm

4/17/4

0.128 +/- 6 h
Thickness 16 cm

4/8/4

0.143
Thickness 12 cm

2/8/2

0.87

 

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The wooden brick concept allows homogeneity of the walls, simply wood and no other materials.  The interior cladding in solid wood provides good inertia and regulates the hygrometry of the house. Also, in summer, the exterior cladding in solid wood absorbs thermal shocks and avoids the over-heating of the interior. The wood fibre which is used as filling ensures the thermal insulation of the whole. This wall system is a compromise between the « Finnish, Norwegian, Canadian » timber type house and a house with a wooden frame.

In order to remain in the domaine of the bio-sourced home and to always keep  homogeneity in the materials, it is advisable that the structure and the insulation of the lower floor be in wood. The latter will be placed on a system of studs anchored in the soil.

As for the roof, it will also be of wood with a system of small traditional latches onto which one can place a tile cover or an insulated steel casing. The ceiling may also be in wood panelling fixed under the latches, onto which a layer of wood fibre of 30 to 40 cm thick will be placed.

The heating, cooling and ventilation system will be ensured by an efficient double flow CMV (85 % yield) which could be coupled with an earth-to-air heat exchanger for extra calorie supplies. This CMV will have a double function, that of airing the house, but also that of maintaining a constant temperature thanks to the recovery of calories in the home, produced by household appliances and its occupants. Moreover, the inertia obtained by the interior solid wood pannels will allow to store and return the heat produced in winter or the freshness in summer. Possibly, for periods of extreme cold, one could install a pellet wood burner which is low in energy consumption.

All of these criteria allow to say that this construction system is within the framework of the new certification created by the State (Label E+C-), more energy-saving and less carbon. This certification heralds the new 2020 norm.

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A simple assembly

Accompanied by an extremely detailed plan which guides the buyer on every step of the construction, the 160 brick will allow you to assemble and install in the simplest manner possible, the studio or room which could even be adjacent to your home.

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