21 Degrees

21 Degrees 21 Degrees: where energy efficiency, health and comfort come together. Heating, ventilation, windows, doors and renewables. Delivered by one trusted team.

Supporting homeowners, architects and builders. A strong proponent of Passivhaus design, GBS offers a comprehensive range of Passivhaus products and services for the UK, and its in-house building team have constructed numerous Passivhaus buildings including the pioneering Denby Dale Passivhaus, Golcar Passivhaus and Stirley Farm EnerPHit projects. It has offices across the nation. Green Building Store and Green Building Renewables are now 21 Degrees.

Three couples. Three homes. One shared Passivhaus project.Bill Butcher and Chris Herring recently spoke to Ben Adam-Smit...
09/06/2026

Three couples. Three homes. One shared Passivhaus project.

Bill Butcher and Chris Herring recently spoke to Ben Adam-Smith on the House Planning Help podcast about their latest project in Marsden: a modest terrace of three Passivhaus homes.

For Bill and Chris, this project brings together decades of experience in low-energy building, from Denby Dale through to the work that shaped 21 Degrees today.

The aim is simple:

to create homes that use far less energy
feel comfortable to live in
perform properly over time
and show what’s possible when the right people work together from the start

It’s also a great example of the thinking behind 21 Degrees.

Start with the building.
Reduce energy demand first.
Plan the fabric, ventilation and renewables as one system.
Make the details work before they have to perform in real life.

A big thank you to Ben for capturing the story behind the project.

You can listen to the full podcast via House Planning Help.

https://www.houseplanninghelp.com/hph400-three-couples-build-a-terrace-of-three-passivhaus-homes/

The headlines keep coming.Energy prices. Supply pressures. New rules. Another “must-have” product. Another reason to fee...
05/06/2026

The headlines keep coming.

Energy prices. Supply pressures. New rules. Another “must-have” product. Another reason to feel like you should probably be doing something.

There is also a lot of noise around low-energy technology at the moment, and it is easy to see how people end up overwhelmed.

The trouble is that headlines rarely tell people what they actually need to do next.

That is where expert guidance matters. Most homes do not need a dramatic reaction. They need clear thinking, sensible priorities and advice that looks at the whole picture.

Estimated savings of around £70 a month.This recent installation includes 9 x 450W all-black solar panels, a 10kW SigEne...
04/06/2026

Estimated savings of around £70 a month.
This recent installation includes 9 x 450W all-black solar panels, a 10kW SigEnergy Controller, whole-house backup, and 2 x 10kWh SigEnergy batteries.

An air source heat pump is also due to be installed at the same property in the next few weeks, making this part of a wider upgrade rather than a standalone install.

03/06/2026

Foundations and groundworks are underway in Marsden.

Sixteen years after Denby Dale, the Passivhaus story continues.

21 Degrees founders Bill Butcher and Chris Herring are now part of a self-build group creating a modest Passivhaus terrace.

It is a new project, but the thinking behind it goes back years.

From the early days of Passivhaus in the UK, through the Denby Dale Passivhaus, to the work that shaped Green Building Store and now 21 Degrees, the same question has stayed at the centre:

How do we create buildings that use less energy, feel better to live in and perform properly over time?

This build gives us a chance to explore that question in practice.

Over the coming months, we’ll be sharing updates from site, short video clips, design decisions, material choices and lessons from Bill and Chris’s experience in Passivhaus delivery.

The aim is simple: to show how careful design, good detailing and joined-up thinking can create homes that are lower energy, healthier and more comfortable.

More from the build soon.

Not every business gives everyone a voice.We’re trying to build the kind of workplace people recommend.One thing we’ve s...
02/06/2026

Not every business gives everyone a voice.
We’re trying to build the kind of workplace people recommend.

One thing we’ve started at 21° is an Employee Forum.

It’s a monthly session with a rep from each branch to share feedback, raise any issues, and actually action improvements.

Sometimes it’s the small stuff that makes the biggest difference. And it’s a simple idea: if people feel listened to and supported, they do their best work. And customers feel that too.

It’s early days, but we’ll keep you posted on what changes come from it.

Waiting can change more than the installation date. It can affect pricing. Product availability. Lead times. And sometim...
01/06/2026

Waiting can change more than the installation date.

It can affect pricing. Product availability. Lead times. And sometimes the quality of the decision itself.

It is not just energy prices shifting right now. Demand is rising. Supply chains are tightening. Shipping, materials and component costs are moving again across solar, heat pumps and ventilation.

That is what tends to happen when more homeowners start looking at energy upgrades at the same time.

Earlier conversations give people more room to think clearly, compare options and make better decisions.

Warmer weather is when overheating should be on the radarThe best time to think about overheating is before summer becom...
29/05/2026

Warmer weather is when overheating should be on the radar

The best time to think about overheating is before summer becomes uncomfortable.

A lot of energy conversations focus on staying warm in winter.

But how a home performs in warmer weather matters too.

Glazing, shading, ventilation and overall design all affect whether a space stays comfortable or starts overheating when temperatures rise.

That is why better-performing homes are not just about keeping heat in. They are about managing comfort all year round.

A home that works well should feel better in every season, not just one.

A tiny handful of people from the UK were in the room.That was the reality in 2007, when our co-founder Chris Herring tr...
28/05/2026

A tiny handful of people from the UK were in the room.

That was the reality in 2007, when our co-founder Chris Herring travelled to his first International Passivhaus conference in Austria with his friend and colleague, Nick Grant, who later became Technical Director at the Passivhaus Trust.

At the time, Chris had been looking at Passivhaus as a possible next step for the business and its work around better buildings and climate change.

There had been a lot of debate in sustainable building circles, and among leading academics, about how far it was really sensible to go with insulation, airtightness and energy efficiency.

Chris and Nick went to find out more.

The conference was chaired by Helmut Krapmeier, then head the Vorarlberg Energy Institute, with around 1,000 delegates, but only a tiny handful from the UK.

What Chris and Nick saw convinced them that Passivhaus made sense as a practical standard built around better fundamentals.

Lower heat loss.
Better fabric.
Proper ventilation.
Careful detailing.
Buildings designed to perform properly over time.

Shortly after Chris' return, Geoff and Kate Tunstall approached the business about an eco-house they were planning. He proposed to them that anything less than a Passivhaus would be a wasted opportunity.

That project became the Denby Dale Passivhaus, one of the UK’s first Passivhaus homes and a major step in the early UK Passivhaus story.
Now, that thinking is being put into practice again.

Chris and fellow 21 Degrees founder Bill Butcher are part of a self-build group creating a modest Passivhaus terrace, designed around practical delivery, careful detailing and long-term comfort, incorporating much of what they have learnt since Denby Dale.

Build It Live West is just around the corner.Building or renovating? This is the kind of advice worth getting early.If y...
27/05/2026

Build It Live West is just around the corner.
Building or renovating? This is the kind of advice worth getting early.

If you’re planning a self-build, renovating a property, or trying to work out the best route to a more comfortable, lower-energy home, come and speak to the 21 Degrees team.

We’ll be at Three Counties Showground, Malvern, on 30–31 May, offering practical advice on heating, ventilation, windows, doors and renewables.

You can speak to Mike Shufflebotham, Luke Gilman and Oisin Stack on stand B20.

Build It magazine

Expected savings of around £260 a month, with an estimated payback period of around 5.5 years.Completed in Southam, Warw...
26/05/2026

Expected savings of around £260 a month, with an estimated payback period of around 5.5 years.

Completed in Southam, Warwickshire, this installation includes solar PV, battery storage, whole-house backup and EV charging for a large home with significant electricity demand, including an outdoor pool.

The installation includes:

39 x 480W all-black Longi panels
Tigo optimisers for full optimisation
12kW SigEnergy Controller
18.08kWh of SigEnergy battery storage
SigEnergy HomePro Gateway for whole-house backup
12kW SigEnergy DC EV charger

A strong example of how a larger system can be designed around the way a property actually uses energy day to day, whether that includes a pool or simply higher overall electricity demand.

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