Passive House Retrofit in Vermont, US

The term airtightness leads us to think of a stuffy, hermetically sealed house, but airtight houses are extremely healthy and economical to run.


Airtightness is the resistance of the building envelope to inward or outward air leakage. Air leakage is driven by differential pressures across the building envelope. Excessive air leakage results in increased energy consumption and can create a draughty, unhealthy, cold/hot uncomfortable building. The mechanisms that create these differences in pressure are combined effects of rising internal warm air, external wind and mechanical ventilation systems.

The correct level of airtightness does not have to be difficult to achieve but it is important to choose the right solution that can ensure the building fabric performance.

Partel recently consulted and worked with Montpelier Construction in Vermont. Chris Clarke Miksic of Montpelier Construction who worked on the project is a certified PHIUS Passive House Consultant (CPHC), PHIUS Builder (CPHB), and one of Montpelier Construction’s founding partners.

The project involved a deep energy retrofit including the range of Partel airtight products and Roxul insulation.


Project type: Passive House Retrofit

Location:  Vermont, US

Building: Single-Family house

Completion: 2018

Airtight system supplied: Partel Vara Plus airtight membrane and Partel Conizo tape.

The stringent air tightness requirements were delivered by using Vara Plus, an internal smart vapour control layer, durable and reinforced for optimal strength. Thanks to the widest variable perm range on the market, Vara Plus allows for optimum summer drying and winter protection. It played a significant role in improving the energy efficiency of the house. It was used to minimize moisture migration through the building envelope thereby reducing the risk of condensation occurring within the structure (interstitial condensation).

Conizo tape was used to fully seal the vapour control layer, to seal windows, corners and to reduce uncontrolled air leakage through the building envelope. Conizo is a VOC free acrylic adhesive with excellent ageing resistance.

Through meticulous attention to detail and by using the best products, the builder was able to achieve the right level of airtightness for this project.

Therefore, in choosing the right building envelope system, the homeowner was able to reduce the energy consumption, protect against moisture and avoid structural damage to the construction.



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