Achieving minimum levels of energy efficiency in our homes is essential to ensuring the health of the occupants, and the durability and longevity of the building itself. It means we can afford to keep them at a healthy temperature as they need less heating and cooling, so reducing the risk of condensation and mould, while also ensuring adequate levels of consistent ventilation removes any moisture and contaminants that would otherwise build up.

Producing an energy model is the primary way to assess how the building will perform before it’s even built, or before the renovation project begins – otherwise it’s just a guessing game. The model allows us to make choices around the amount of insulation, the components we use, the windows and type of glass; to balance cost with the level of energy efficiency we require. Rather than broad-brush R value requirements, we can assess the requirements of the specific building in a specific site, resulting the materials and costs being put into the correct places to achieve the required performance.

Once the specification is decided, it then needs drawing and documenting to ensure the three building control layers are continuous – Weathertightness, Thermal envelope and Airtightness, and to resolve the connections between different materials and junctions.

Joe Lyth joined the ParkaWrap team to work through both of these elements. The first step was to survey, draw up and thermally model the existing building to see what our starting point was. The result was a building that used nearly 170kWh/m2/year to achieve a healthy interior temperature of 20 degrees – that’s 11,949kWh/ year, or $3,804* just for heating.

Once we had the baseline we could see what insulation and glazing would be required, and what level of performance would be achieved. The parkawrap process is to insulate externally, replace the windows and not touch the interior where possible, so the decision was to use external insulation on the walls, full fill the 140mm floor with insulation and add 290mm insulation to the ceiling space. The windows were to be replaced with Starke UPVC joinery, and a balanced ventilation system was to be installed.

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These changes immediately dropped the modelled heating demand by over 83%, and within the realm of the PHi Low Energy Building Standard – an aspirational target to aim for!

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Once the material specification as decided the evolving task of documenting the construction details began. A detailed 3D model of the building was developed alongside the 2D details and the energy model, to paint a full picture of the ParkaWrap process. As products were installed on site the details were updated to reflect the as-built process, while the model and details themselves highlighted areas and junctions that would require additional attention and thought, which was communicated back to site. A truly collaborative process that incorporated improvements throughout!

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*(assumed 0.30c/kWh + 0.60c daily rate)