Thermal and acoustic Insulation; Energy performance standard and thermal inertia

Thermal insulation

The insulation volume for the house alone is around 100m³. The vertical and horizontal timber frame construction consists of FJI composite I beams combined with LVL (laminated) horizontal beams. The outer walls are 33cm thick, 27cm of which was insulated with wood wool plus a low ventilated air outside cavity of 3cm. Particular attention has been paid to avoid thermal bridges and air leaks.

The roof consists of solid wood Douglas pine trusses with a height of 29 cm, which are insulated at the top with 35mm wood wool plates so that thermal bridges are avoided here too (Although insulating, the insulation factor of wood is only 30% of that of the wood wool insulation). The total roof insulation is therefore 32.5 cm plus an inside air cavity of 3 cm.

All windows and outside doors accommodate triple glass, whereby the reinforced PVC profiles, of German manufacture, are also super insulated.

The Fakro roof surface windows also consist of triple glass and are surrounded by an additional insulation layer.

The 30cm thick double reinforced and floating concrete slab is fully insulated. At the bottom, it rests on a 64 cm thick insulation layer of puffed glass chunks from the Technopor brand. The sides of the concrete slab were surrounded by a 14cm PIR insulation board.

The garage which is separated from the main house by a double door entrance sass, has been insulated with 12cm of Rockwool in the walls and 16 cm in the roof. Same is valid for the Garden Work center.

Acoustic insulation

Given the wooden frame structure, special attention has been paid to the acoustic insulation so that there is minimal sound transmission between the different rooms on the one hand and the outside of the house on the other. This is essential for a pleasant living comfort.

The outer walls and the roof with their thick wood wool insulation (fixed plates combined with wood wool flakes) sufficiently dampen the outside noise. This is also the case with the triple glazing.

It is therefore especially important to provide good acoustic insulation between the different floors and between the different rooms. Effective acoustic insulation dampens both vibration and contact noise. This requires both soft damping material and mass.

The floors between the different floors are 33 cm thick in total and consist of 2 parts:

  • The bearing surface part with the I beams of 24 cm of which the hollow spaces were filled with wood wool (density of 30kg / m³) and closed at the bottom by a 10mm MGO (Magnesium cement) plate and at the top with a 20mm thick MGO plate. Since MGO plates are non-flammable (class A), the floors are protected against fire.
  • On top of the support structure there is a sandwich floor consisting of:
    • A wood wool board of 30mm
    • A floating MGO plate of 20mm glued in the tongue and groove
    • An acoustically inhibiting wood wool board of 7mm
    • A floating layered composite parquet of 15mm

This layered structure with its combination of damping and solid materials ensures a very good separation of the sounds between the floors.

The floors of the bathrooms, the dressing and the laundry room consist of a reinforced (iron nets and glass fibber’s) screed that rests on a damped wood wool plate of 7 mm. A stone floor is paved with a flexion glue.

For the wooden partition walls on the first and second floors between the different rooms, damping materials were also combined with solid plates. They consist of:

  • A MGO plate of 10mm
  • A wooden frame made of pine SLS beams
  • A 70mm Rockwool SONO plate that fills the compartments between the vertical beams
  • A double MGO plate of 2 x 10mm

This construction contributes to minimal noise pollution.

The walls on the ground floor consist of 10 cm thick solid Silca glue blocks of the Xella brand. They were plastered on both sides with a 1 cm thick natural plaster layer. This composition not only contributes to a limited acoustic transfer between the walls, but also to a greater thermal inertia on the ground floor

K and Ew value (PEB: Building Energy Performance)

The construction of the outer shell results in a K value of 22.

The Ew value takes into account all the different aspects related insulation, ventilation, energy consumption, energy-saving and energy-generating devices. The official calculated value is 14. Compared to the current standard being , this is 3 times better. So this is a house that is far ahead of its time and will withstand the test to the future with brio.

Thermal inertia

A major potential disadvantage of a highly insulated timber frame construction is overheating during the summer. This can be all the more the case during the increasing heat waves.

To limit this overheating, the construction partly consists of a hybrid structure: On the ground floor, the concrete slab, insulated from the outside, forms part of the living space together with the screed and the floor tile. This creates a volume of 40m³ thermally inert material. This is combined with the massive Silicate stone inside walls on the ground which create an additional inert volume of 9 m³.

Furthermore, many but limited surface window surfaces were built in. This provides abundant light but limited over heating of the rooms.

However, all this will not prevent the house from heating up during a prolonged heat wave. To prevent this, a reversible air / air heat pump is provided which guarantees that the house can be cooled during several continuous hot days.