Is this how all new homes should be built in 2023? (Case Study)

MVHR kitchen extract grille with grease filter in luxury home

Heat, Space and Light Ltd has completed the design, supply and commissioning of a Passivhaus-specification MVHR ventilation system for a luxury new build in the northwest of England. The home was also tested by our building airtightness team and achieved an incredibly airtight result of 0.76 m3hr/m2 @50Pa. It’s only slightly shy of a fully-certified … Read more

Case Study: Cool, low energy renovation for London townhouse with MVHR

Heat, Space and Light Ltd has completed the design, supply and commissioning of an MVHR system in a four-storey London terraced home. The property has undergone a deep retrofit to EnerPHit criteria, which is the retrofit standard for Passivhaus. Passivhaus building standards are a stringent methodology using high levels of insulation, airtightness and ventilation with … Read more

Early construction forensic air pressure test improves new building’s fabric air permeability by 50%

Forensic Airtightness Testing and Strategy by Heat, Space and Light Ltd has helped a new build home in Dorset achieve a drop in its final airtightness rate that will result in £100s of heating savings every year, turning it from a leaky home to an airtight home. Forensic air testing improves Air Permeability from 6.4 … Read more

How airtightness testing differs between Building Regs and Passive House – and why it matters so much

Using a smoke pen to detect leaks during airtightness testing

Building Regulations Part F wants to know how much air (in m3hr) passes through each metre square area of the fabric (m2). This is the Air Permeability (AP or figure of the building. To get the AP figure, one calculates the volume of air in the property. Then one calculates the total external envelope … Read more

What’s wrong with a Passive House?

Forensic air test of a very low energy home almost Passivhaus

Why aren’t passive houses (AKA Passivhaus) mainstream? Why isn’t every new home built in the UK produced to the design specifications of passive houses? Here I’ll go through what’s bad about passive houses, whether it’s true, and what might be done to fix the problems. 1) Passive Houses are boxy and ugly Passive houses are … Read more

How to work out the Passive House Form Factor

Complicated form of a UK home dormer will require more insulation as proportion of external area to floor area increases

The Passive House Form Factor quantifies the relationship between the living area of the building and the total amount of surface area that heat can escape from. The calculation is simple: Total heat loss area ÷ floor area = Form Factor The Form Factor of a building is key in low energy design because it … Read more

So who are Passive Houses for?

Airtightness Test Kit mounted in hallway of London retrofit 2021

Are eco-friendly passive houses for rich people? Eco warriors? Self-builders? Housing associations? Or are they only the preserve of our more logical, engineering-minded continental cousins in Germany? Passive Houses are for everyone. To build a Passive House, ie, one that runs at ten per cent of normal household bills, doesn’t need any extra technology like air-source heat … Read more

Can you open the windows in a PassivHaus?

Zehnder Comfoair MVHR installed in utility room

One of my friends remarked today that their colleague was asking about that “German eco home, the one where you can’t open the windows…” The idea that you can’t open the windows in a Passive House comes from a misconception regarding the clever way that Passive Houses regulate the heating and cooling of a home. … Read more

How to calculate how much energy your windows will save from its U-value

Old cottage made airtight and insulated with woodfibre insulation

The number assigned to a building fabric element (eg, a window) that represents its thermal resistance is called its U-value. A U-value tells us how quickly or slowly it takes for heat to pass through it. Fabrics with lower U-values are better insulators than those with higher U-values. Part L of the UK Building Regulations … Read more

The four ways dodgy builders ruin new-build low energy homes

Not many UK builders have embraced PassivHaus principles yet. Below are a few ways that builders in the UK can ruin low energy homes, either by ignoring or failing to understand the new wave of low energy design and build techniques that help create modern, ultra-comfortable, money-saving eco homes. 1) Ignoring the airtightness membrane UK Building … Read more