Eco building & Passivhaus

Eco houses, low-energy houses… call them what you will, they’re buildings that use very little energy to heat and cool. If they meet a very rigorous set of standards, they can be certified as a Passivhaus building.

All the properties we work on are low-energy buildings and several have full Passivhaus certification.

A typical low-energy building will be highly airtight, very well insulated and use a mechanical ventilation and heat recovery (MHRV) system. Together, these features reduce the amount of energy needed to maintain a comfortable temperature and regulate moisture all year round.

How? Because they work as a system to:

eliminate draughts that make you feel colder
stop warm air escaping from your building in winter, and prevent warm air coming in from outside in summer
capture heat generated by appliances and occupants inside the building, redistributing it in winter or expelling it in summer to maintain the internal temperature you want
capture and regulate moisture created in the building, to prevent condensation

Retrofitting?

If you’re renovating an older building, there’s a special Passivhaus standard called EnerPHit. It’s a slightly relaxed standard, recognising the constraints often faced with refurbishing properties, where it isn’t feasible to meet the normal Passivhaus standard.

About the Passivhaus standard

Passivhaus is the leading international standard for low-energy design.

Over 37,000 buildings have been designed, built and tested to this standard worldwide, including several that have been built using our frames at their heart.

What is Passivhaus?

“Passivhaus buildings provide a high level of occupant comfort while using very little energy for heating and cooling. They are built with meticulous attention to detail and rigorous design and construction according to principles developed by the Passivhaus Institute in Germany, and can be certified through an exacting quality assurance process.”

Passivhaus Trust

Benefits: why build this way?

Low heating costs

Heating requirements in a Passivhaus building are 75% less than you’d achieve with traditional build methods*. That’s certainly the experience of our Passivhaus clients, who tell us that their heating bills are just £100-150 a year.

Better air quality

The definition of Passivhaus is driven by air quality and comfort, says the Passivhaus Trust. Your building’s air circulation system filters the air in your home, bringing in fresh air from outside. Clients who live in passive houses have told us they’re virtually free of dust as well.

Better for the planet

Using less energy to heat your home means you’re also reducing your carbon footprint. More than a third of the UK’s greenhouse gas emissions come from buildings, and houses account for 66% of those emissions, according to the Committee on Climate Change.

Meet tougher Building Regs

Building Regulations for airtightness are becoming ever tougher. A construction method like ours allows you to very comfortably meet the current target set out in Part L of the regulations. In fact, one of our recent buildings achieved 0.11 air changes per hour, which was well within the Passivhaus target of 0.65 air changes per hour or fewer. To quote the Passivhaus Trust, “The Passivhaus standard therefore gives a robust method to help the industry achieve the 80% carbon reductions that are set as a legislative target for the UK Government.”

Moisture control

The mechanical ventilation system in your airtight house removes excess moisture from the air, preventing condensation. The materials used in our frames also contribute to moisture management. We use breathable components that allow moisture in the air to pass out of your building, while preventing dampness permeating in from outside.

Find out more about moisture control in airtight buildings in our blog post

How to achieve Passivhaus standard

very high levels of insulation
extremely high performance windows with insulated frames
airtight building fabric
‘thermal bridge free’ construction
a mechanical ventilation system with highly efficient heat recovery
accurate design using the Passive House Planning Package (PHPP)

Passivhaus performance targets *

Primary energy demand: ≤ 120 kWh/m2. yr
Space heating demand: ≤ 15 kWh/m2. yr
Space cooling demand: ≤ 15 kWh/m2. yr
Specific cooling load: ≤ 10 W/m2
Airtightness: ≤ 0.6 air changes/ hr @ n50

*Source: Passivhaus Trust

Visit

Passivhaus guidance

If you’d like to find out more about Passivhaus, we’d highly recommend visiting the Passivhaus Trust website. It’s packed with information about the Passivhaus standard, and you’ll find lots of interesting case studies and guidance.

Their publication ‘Technical Guidance – How to build a Passivhaus: Rules of Thumb‘ is very helpful.

Visit