More Proof: Green House Designs do Reduce Energy Costs

Posted on 09. Jan, 2012 by in Articles

green house designs reduce energy loss

Measured heat loss parameter of the GHA test properties, compared to the stock, past, present and predicted building regulatory requirements.

The Good Homes Alliance (GHA) in the UK recently conducted post-construction testing of four energy-conscious homes that reveals that green house plans do indeed save energy compared to stock homes. Launched in 2010 as a project sponsored by the Energy Saving Trust (EST) and Communities and Local Government (CLG) groups, this program aimed to test four energy efficient dwellings at three different developments, post-construction, to compare actual measured performance with predicted performance.

The report looked at three main issues that typically cause heat loss in conventional homes:

  • Thermal bridging, which can account for 30% of a home’s heat loss. This includes any junction where building structure changes, such as junctions of floor and roof structures with external walls and details around window and door openings, as well as mortar joints, timber joists, etc.
  • Thermal bypasses, where heat bypasses the conductive or conductive-radiative routes between two regions.
  • Air leakage, which can account for 50% of a home’s total heat loss, is any area where air flows between gaps and cracks in the external structure of the building.

The report measured the heat loss in these houses using several testing and monitoring methods, including co-heating tests, heat flux measurements, thermal imaging, and air leakage tests.

Thermal imaging used to test the green house designs

Thermal imaging used to test the green house designs

Additionally, the report details various performance monitoring to determine how energy-saving features perform in real life situations.

The report concludes that, although there is usually a slight discrepancy between the predicted and measured heat loss in the four dwellings tested (between -1% for Test Dwelling 3 and 29%, for Test Dwelling 4, though because total heat loss is relatively low, the performance gap in absolute terms is very small), overall the structures performed far better than stock houses built today. The chart shown here illustrates this point clearly.

The important conclusions for those interested in answering the question as to whether a green home is worth the extra cost and effort are as follows:

  • All four Test Dwellings achieved very low levels of actual measured heat loss.
  • All Test Dwellings out-performed standard UK building regulations (which are more stringent than those in North American, generally speaking).
  • Simple design features like better wall and floor junctions, ceiling gable wall junctions, and the like can improve thermal performance by up to 85%.
  • Green building designs including airtightness can reduce carbon dioxide emissions by up to 10%.

And for those still concerned about predicted and actual performance gaps, you’ll be encouraged to know that previous tests showed a 60% gap, compared to an average of only 14% here.

Related posts:

  1. Green Roofs: Energy Efficiency for Winter Homes? Yes!
  2. Passive House Building Standard – Good for North America?
  3. Take a Tour of Passivhaus Green Home Designs in Austria with Hammer and Hand
  4. Russian Active House to Incorporate Dynamic Green House Concepts
  5. New Report: Green Homes Consume Less Water

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