Green retrofit: a tour of BGEN’s HQ office

What does it take to retrofit a typical modern office for Net Zero? E&T got a tour of BGEN’s HQ in Warrington to find out.

Most companies don’t have the luxury of building a brand new, carbon-neutral or net zero office building – and that may not necessarily be the best thing for the environment anyway. They have to make the best of what they’ve got. 

In Warrington, engineering solutions business BGEN is on that journey. E&T started a tour of their offices and the measures they’ve taken so far by asking what net zero means to them.

Net zero v carbon-neutral

“What a lot of organisations have done, and you’ll see this a lot, is they will declare carbon-neutral. Now, that doesn’t mean a lot, it means they bought trees, that’s what carbon-neutral means,” explains chief digital officer Simon Clarkson. “And they’ve not necessarily made any effort whatsoever to reduce the carbon footprint of their business, all they’re doing is offsetting what they generate. It’s not sustainable. If you were to offset the carbon production of the UK, annually, you would have to plant an area the size of India with trees every year.

So, we’ve taken the next step, which is to go net zero. Net zero means you reduce everything you possibly can and then you offset what’s left.  And then you look for more improvements constantly. The step after that is science-based targets (which we’re in the process of signing up to): that’s where you start to bring your offsets down to nothing. And you build targets around reducing your carbon that are consistent with a 1.5 temperature degree rise.” 

The BGEN HQ tour

Clarkson took E&T around BGEN’s HQ building in Warrington, explaining the various measures and what effect they’ve had as we went. 

BGEN HQ 3d render

BGEN’s Warrington HQ showing the solar panels and other measures.

Image credit: BGEN

External lamps

Small wind turbines and solar panels to power the low-energy lamps on the existing posts. “As the wind picks up, they’ll turn and produce a charge voltage and, along with solar, that charges their batteries,” explains Clarkson. “That’s used for all our car park lighting and there is a mains connection into there just to top up the batteries when it’s a bit dull, and there’s not quite enough wind.”

Rooftop solar panels

Around 50 panels “that provide 21-kilowatt peak generation. That’s enough to charge an EV, maybe two, and all of our lighting demand for a day. Now, you obviously don’t get that all year round, it’s probably producing about a kilowatt to a kilowatt and a half today in the dull conditions. But in the summer, it goes up to 16.”

Air source heat pump

Air source heat pump

Image credit: BGEN

Hybrid VRF

BGEN replaced the four gas boilers in each corner with an air source heat pump HVAC system for heating and cooling. “We went a step beyond just using air source heat pumps as well, and we’ve actually got what’s called a hybrid VRF – that’s hybrid variable refrigerant flow. So, the flow of the refrigerant is varied to accommodate the cooling and heating demand. And the hybrid part means that the refrigerant gases only operate in a fairly small closed circuit, which is predominantly outside the building. That means that you’re not bringing refrigerant gases into the building apart from into one unit, and there’s less refrigerant gas, so it’s less likely to leak and contaminate the atmosphere itself – because refrigerant gases themselves are a greenhouse gas.

“The fact that you’ve got individual water lines going to each room means that you can actually have one room heating and another room cooling. The heat that you extract from one room effectively gets transferred to another room you’re trying to heat up.  It’s really efficient.”

BGEN office lighting

Image credit: BGEN


“We installed all of these new LED light fittings. They’re not just bog-standard LED light fittings either; they are all intelligent, so they all communicate with each other. And they’re pre-commissioned with a certain amount of intelligence. I came in this morning at eight o’clock, and most of the place was dark. As I walked through, the lights on the stairs came up, and then they came up ahead of me, before I arrived at the landing.  And it does all this kind of stuff for you. But it also knows if people are working in the area, so they’re not constantly switching off just because you haven’t moved. But each one pretty much has an occupancy sensor, and they all talk to each other.”

The dashboard for BGEN's energy production and usage

Image credit: BGEN


“So, all of this data we’re collecting, I built a machine learning model using the gas consumption for a two-to-three-year period, and used heating degree data to train the model, so that it could predict for a given heating degree value, and how much energy our gas heating system would use. That allows me a basis to work out what the energy saving is between the HVAC system and the gas system. I’m just starting to collect that data now and to analyse it. You can do that same thing using conventional methods, but the purpose of doing it using machine learning is to start to incorporate other factors which wouldn’t traditionally be incorporated. So we’re monitoring demand for power, as well as occupants. That’s basically reading door entry systems. We know how many people are in each building at any one time. And then we can feed that into a machine learning model to also measure ‘how much energy do we use when this many people are in?’ ‘What’s the temperature setpoint in each room, how does that affect the energy consumption?’ All kinds of stuff we can start to do later. This is using ThingWorx, by the way.

I can give it more intelligence and start saying things like, Paul’s got the boardroom booked for four hours on Friday, so on Friday an hour before Paul’s got the meeting room booked we’ll lift the temperature setpoint to the standard setpoint with the rest of the building. And then when he’s finished with his meeting, we’ll drop it back down again and run it at a holding temperature so we’re not heating an empty room for no particular reason. And then we can build in the occupancy information from the lighting system. So Paul’s meeting was supposed to finish but there are still people in this room, let’s not reduce the heating just yet. We can start to give it some real intelligence beyond what you might do just with the building management system. We’re using similar principles but lifting it a level.”


“We’re also measuring the amount of water that we use. We’ve fitted a flow meter into the water incomer. You can see there yesterday, we used just over 1000 litres. We changed all the taps in all the bathrooms to push taps, low-flow versions to reduce the amount of water they use, and dual-flush units on the toilets. We previously consumed close to 3000 litres a day. It’s a massive difference.”


Fitted on the inside with solar film which reflects the sunlight. A simple measure that’s had a “massive effect”. 

“You know, that’s something you can do really easily. And for health and safety reasons and to make the installation easier, we fitted it in the inside. We didn’t even have to put scaffolding up on the outside to do.” As the temperature rises, people start opening windows but that destroys the planned ventilation. “We found after fitting this, that HVAC wasn’t even starting to cool until lunchtime. It’s incredible the effect it’s had.

The product installed is called Sentinel External Silver 20 OSW Window Film.


“The flooring has been replaced and there’s two reasons for that. One is its thermal properties are better so it produces less of an issue with solar gain and the heating of the building. The other is that it’s made from recycled bottles. So, the flooring in itself is sustainable.”

Certified renewable tariffs

Energy that BGEN doesn’t generate itself on site it buys through certified renewable tariffs. “We’re not fully, fully powered by the solar cells. With net zero you reduce the amount of carbon that you’re producing as low as possible, and then offset whatever’s left. As opposed to carbon-neutral, which is just offset. So, in order to do that, we changed all of our electricity tariffs in all of our buildings that we own to a certified renewable tariff. Certified renewable tariff means Ofgem has certified, or our supplier certifies, that the energy is generated from renewables. It’s not the same as oh yes, it might be renewable. They’re actually saying the amount of energy you’re consuming, we are procuring from renewable sources.”

But the grid is a mix so doesn’t one customer buying all renewable energy just mean that by default another is buying all fossil fuel?

“Yes and no.  Last year was the highest generation of renewable energy on the UK grid, it’s about 40 per cent. That’s the highest it’s ever been. One reason it’s as high as that is because of demand. So the more people that are going to be specifying renewable energy, the more people prepared to provide it, which provides more reason to invest in it.  But we accept that as well, so we could have, and it would have been cheaper to, just change our tariff renewal and not bother putting those 50 cells on the roof. But by putting those 50 cells on the roof, we’ve got a surplus of energy sometimes, which goes back into the grid. And also it offsets the amount we’re drawing from the grid, which makes more renewable energy available for other people.”

The purpose of the certification is your supplier is only procuring renewable energy for your demand. That’s what the certification means, so they’re guaranteeing that. They can’t guarantee that what’s delivered to you ultimately was generated that way, because it’s all electrons.  But they’re feeding that amount into the grid. So you’re not increasing the amount of fossil fuel generated energy through your demand.

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