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๐——๐—ฒ๐—น๐—ถ๐˜ƒ๐—ฒ๐—ฟ๐—ถ๐—ป๐—ด ๐—ต๐—ถ๐—ด๐—ต ๐—น๐—ฒ๐˜ƒ๐—ฒ๐—น๐˜€ ๐—ผ๐—ณ ๐—น๐—ถ๐˜ƒ๐—ถ๐—ป๐—ด - ๐—ง๐—ต๐—ฒ ๐˜€๐—ถ๐—ด๐—ป๐—ถ๐—ณ๐—ถ๐—ฐ๐—ฎ๐—ป๐—ฐ๐—ฒ ๐—ผ๐—ณ ๐—”๐—ถ๐—ฟ-๐˜๐—ถ๐—ด๐—ต๐˜๐—ป๐—ฒ๐˜€๐˜€ & ๐— ๐—ฉ๐—›๐—ฅ ๐—ถ๐—ป ๐—ฃ๐—ฎ๐˜€๐˜€๐—ถ๐˜ƒ๐—ต๐—ฎ๐˜‚๐˜€ (๐—ฃ๐—›) ๐—ฑ๐—ฒ๐˜€๐—ถ๐—ด๐—ป:

Passivhaus standards ensure that the combination of Air-tightness & MVHR systems work together to deliver high levels of living. These essential components of PH design have been proven to provide occupants of buildings with high-quality filtered air, thereby improving living standards at ๐—ต๐—ผ๐—บ๐—ฒ,while enhancing concentration and comfort levels in ๐—ฒ๐—ฑ๐˜‚๐—ฐ๐—ฎ๐˜๐—ถ๐—ผ๐—ป๐—ฎ๐—น๐˜€๐—ฝ๐—ฎ๐—ฐ๐—ฒ๐˜€ & the ๐˜„๐—ผ๐—ฟ๐—ธ๐—ฝ๐—น๐—ฎ๐—ฐ๐—ฒ.

Air-tightness is crucial to most modern-day building designs. Measured usingโ€˜ air-permeabilityโ€™ rates, the UK Building Regulations 2010(2021 edition) Part L, defines air permeability as โ€˜the measure of airtightness of the building fabricโ€™.

UK regulations require a minimum standard for air permeability of new buildings- โ€˜8mยณ/(h.mยฒ) @ 50 pascals (Pa)โ€™, however, generally, it's advised to design to no more than 5mยณ/(h.mยฒ) @50Pa.

But how does this help us understand the significance of Passivhaus design?

Essentially, the more airtight the building, the less heat is lost from it, while mitigating thermal bridges. The air change rate for new-build PH buildings must achieve a maximum of 0.6 air changes per hour when tested @50Pa,equating to a hole less than the size of a 5p coin in the external building envelope, for every 5mยฒ of envelope! Compared to UK Building regulations, PH design is approximately 15 times more airtight, significantly mitigating energy consumption required for heating or cooling.

An airtight wrap requires efficient ventilation of the internal spaces. For the PH design model to perform efficiently, a good quality Mechanical Ventilation and Heat Recovery (MVHR) system needs to be introduced.

An MVHR system is a genius invention! It works by extracting the stale air from โ€˜wetโ€™ areas like kitchens and bathrooms, which then passes through a mechanism called a heat exchanger, effectively recovering its heat. The stale air is efficiently extracted to atmosphere & fresh air is brought in from outside through insulated supply ducts. On entry, the air is efficiently filtered,& warmed with the recovered heat.

Even though PH design requires effective air-tightness & efficient MVHR systems, one might think that windows should not be opened, however it is encouraged! Openable windows help assist night-time cooling of PH buildings during the summer months.

The significant coupling of Airtightness & MVHR, helps deliver a healthy, comfortable, energy conscious environment for all occupants in Passivhaus designed buildings.

As certified PH designers, we at Lytle Associates Architects can help you realise these standards. Contact us today:

โ˜Ž๏ธ (+44) 01483 301 661

๐Ÿ“จ
prawsthorn@lytle-associates.com

๐ŸŒ
www.lytle-associates.com

LytleAssociates Architects
PassivhausTrust
PassiveHouse Institute | iPHA
Architects Registration Board
RIBA

 

โ€

Posted on
July 28, 2025