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Fri Mar 13, 2015



One of the key components required in achieving optimal air quality and comfort in a Passive House is an appropriate solution for heating, cooling and ventilation. 

The ground breaking products that were used in the Darmstadt pilot home, including high-efficiency mechanical ventilation heat recovery (MVHR) systems, made way for a new line in Passive House compliant components.

Thermal Insulation and Heat Recovery

By design, a Passive House retains high levels of passive heat gains.   Consequently, only a minimal amount of additional heating needs to be supplied.  Much like a thermos flask holds heat, the concept is based on delivering excellent thermal insulation.  In turn, a highly efficient heat recovery system enables up to 95% of the heat to stay indoors and so the need for an active system, such as central heating, is used solely as a supplement.  Of course, minor intervention is inevitable so processes are controlled in such a way that the required goals are met with minimum effort.

Ventilation, ventilation, ventilation!

As draughts aren’t the best way to ensure a comfortable indoor climate, it is essential that the dwelling is adequately ventilated.  Traditionally this would be achieved by opening windows, but in a Passive House the heat recovery ventilation system delivers a far superior job of providing consistent fresh air whilst exhausting stale, used air outside – so whilst you can naturally open external doors and windows in a Passive House, the beauty of its design means there is virtually no need to!  Additionally, the airtightness standards required in a Passive House prevent the structure from leaking moist indoor air through the fabric of the building and eliminate the risk of mould growth allowing for a healthier, more comfortable living environment.

Appropriate solutions from planning to completion

The key to achieving good indoor air quality and comfort is an efficient, balanced ventilation system with the added benefit of heat recovery.  In a Passive House, a minimum of 75% of the heat from the exhaust air is transferred into the fresh air via a heat exchanger.  A Passive House accredited heat recovery ventilation system must provide fresh and clean air at a comfortable temperature without draughts or cold spots along with low levels of sound emission and annual energy savings of between 75% and 90% (compared to traditional properties).

When considering the correct heat recovery ventilation system to install, it is wise to seek the advice of a Passive House specialist, such as Zehnder, who will be able to guide you through the process from planning appropriate solutions to installation, operation and maintenance.  Many factors need to be considered to ensure that the Passive House Standard is achieved and, as such, a Passive House should be treated as more than a sum of its parts to ensure that all components work together to achieve the required results.

To find out more about heating and cooling a Passive House download our ventilation buyers guide here.





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