Low Carbon House Design | Active thermal insulation and Roof Design | Part 4





Insulation : Active Thermal Insulation

‘Active thermal insulation’ will be used for achieving the thermal efficiency of the structure.

The technique of Active Thermal Insulation has been invented by Hungary, BT & Sons Ltd. Their technique involves use of the temperature of the soil for thermal insulation. The coils are applied all around the walls of the house. The coil is connected to a soil probe or a soil absorber and the liquid in that flows by using a small (50W – 70W) flow pump. This helps to minimise the heat loss of the building. It also helps to cool the interior of the house in summer and reduces the external heat load in summer. The temperature of the Earth is nearly constant +8 ° C to +12 ° C all year round. This system requires to be used in combination with the heat pump.

 

Active Thermal insulation

Active Thermal insulation.  The picture shows the coil runs all around the walls and the roof and is connected to the ground source heat pump.    Source: activethermalinsulation.com

According to the Passivhaus standard, the building needs to have super insulation with low U-value. The effectiveness of a material as an insulator in buildings is measured with the help of U-value, the lower, the better is the building performance. It is known as thermal transmittance (Shomera House Extensions, 2012).

The major benefit of using ‘Active Thermal Insulation is that same efficiency can be achieving using less thicker walls (Active thermal insulation, 2011) which means more space would be release. In Brighton, the land is expensive and an integrated construction method can be utilised to achieve both energy and space efficiency.

Walling material

Neopor cellular lightweight concrete (CLC) will be used for walls, roof and floor.  The benefits of using CLC blocks are tremendous weight reduction, high thermal insulation, optimum fire rating, substantial material saving (no gravel, little cement, less steel required in structure and foundation, easy to construct and produce, low embodied energy material). CLC blocks are available in a variety of shapes and sizes (Source: Neopor.com).

The Neopor CLC blocks used will be 600mm x 440mm x 250mm. These are lightweight interlocking blocks. The pipe coil is placed in part of the CLC block filled with concrete in a way such that the thicker insulated part of the brick is placed at the interior of the building and the thinner insulated part remains exposed to the exterior with active thermal insulation at work.

active thermal insulation

Active thermal insulation. Neopor Cellular Lightweight Concrete blocks to be used the construction of walls of the low carbon house at Grand Parade Campus, University of Brighton

According to the experimentation performed by the BT & Sons Ltd, Hungary, the U-value of the walls achieved will be 0.09 W/m2K.

Flooring

Source: activethermalinsulation.com The figure shows how the coils are laid to provide underfloor heating and all around the walls.

Source: activethermalinsulation.com
The figure shows how the coils are laid to provide underfloor heating and all around the walls.

 

Materials to be used for flooring of the low carbon house

Ground floor

Neopor insulated lightweight concrete blocks with coils laid all over the blocks for the purpose of active thermal insulation.

Isometric view showing the layout of coils over the CLC blocks.

Isometric view showing the layout of coils over the CLC blocks.

Section showing the flooring to be laid with coils embedded for to achieve high thermal performance.

Section showing the flooring to be laid with coils embedded for to achieve high thermal performance.

Active thermal insulation performs the task of underfloor heating. Also, solar radiation strikes the ground floor through large south facing windows.  Hence, to increasing the space heating efficiency, thermal mass is to be located on the ground floor (Pitts and Lanchashire , 2011).

Roof Design

A pitched roof will be constructed of timber frame truss rafters. It will be a standard timber truss.  The depth of the rafters will be 300mm. Sheepwool will be used for insulating the roof. A breathable membrane will be installed below the roof. Oak shingles will used to cover the insulation as roof tiles. They are natural materials and do not require installation of waterproof membrane and long for years (Jones, 2009). The U-value for a timber roof is 0.15-0.10 W/m2K. The slope of the roof is towards the south (Pitts and Lanchashire, 2011) for in order to increase the efficacy of solar PVs and solar collectors on the roof. Also, noggins will be provided for wind tightness.

 

Below are the steps to designing a low carbon house:

Eco House Design : Part 1Introduction to the Eco House Design Guide
Design Methodology : Part 2
Eco House Design: Part 3

  • Climate of Brighton and Hove
  • Orientation of the building
  • Building design, construction and low energy specifications
 Eco House Design : Part 4

  • Insulation: Active Thermal Insulation
  • Roof Design
Eco House Design: Part 5

  • Windows and skylights;
  • Door air-gaps
  • Airtightness
  • Thermal Bridging
  • Monthly Energy Demand Profiles
Eco House Design : Renewable Energy Sources| Part 6

Ground Source Heat pump

 Eco House Design : Renewable Energy Sources| Part 7

Solar Electricity Generation

Eco House Design : Renewable Energy Sources| Part 8

  • Rainwater harvesting system
  • Mechanical Ventilation with Heat Recovery

Eco House Design : Renewable Energy Sources| Part 9

Annual Energy Balance

Eco House Design : Part 10 | Conclusion


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