GenFree™ Case Study Balfour Beatty

GenFree™ Case Study Balfour Beatty - Boss Cabins - We Mean Business

UK welfare manufacturer Boss Cabins has recently collaborated with the country’s leading construction company Balfour Beatty to prove our new generator-free welfare cabin concept – Deep Green GenFree™– on one of their busy worksites in Avonmouth, Bristol.

PARTNER:Balfour Beatty
CABIN MODEL:Deep Green GenFree™ Canteen Twin 12 – 7 person unit with twin fresh water toilets
DATE RANGE:16th Feb – 20th March 2023 inclusive (7 days per week)

General Synopsis

This joint trial between Balfour Beatty and Boss Cabins set out to prove beyond doubt that a Deep Green GenFree™️ welfare cabin could operate perfectly with full functionality all year round without the need for a diesel generator with all its associated fuel consumption, emissions, servicing and repair costs.

The Balfour Beatty trial was carried out using the smallest 12ft GenFree™️ cabin size, where less room is available on the outside of the cabin to deploy solar panels, but which still has a relatively high energy requirement for with up to 7 people at one time using it throughout the day. It was also carried out during the months of February and March when less solar PV is available from direct sunlight.

From the 24/7 monitoring and reporting of occupancy and power consumption data, we know that this cabin was being used extremely heavily by Balfour Beatty staff during the 33-day period with much higher occupancy and power consumption than generally expected in a standard welfare cabin.

Occupancy in the Balfour Beatty cabin was regularly 15-18 hours per day 7 days per week, whereas we would normally expect a Canteen-style welfare cabin only to be occupied during breaks averaging maximum 4 hours per day, 5 hours per week. The cabin has been vacated for only circa 30% of the period that the unit has been under test, whereas we would expect a welfare Canteen cabin to usually be vacant for a minimum of 88% of the week. Use and occupancy has consistently continued overnight and through the weekend – conditions that are not normally experienced in welfare units – but a perfect test to prove the viability of the GenFree™️ cabin’s technology in the harshest of conditions.

During the 33 day period of the trial, despite the extreme usage, the GenFree™️ cabin performed with full functionality at all times, with the battery state of charge (SOC) generally remaining above 75% for the majority of the time and only dipping to 54% during the period with the worst weather conditions (see SOC table below).

The low-consumption heater used just 15.8 litres of fuel during the entire period.

According to our usual calculation comparing a standard ‘eco’ welfare cabin (with 12V lighting and USB charging) with normal occupation and an estimated generator run time per day of 4 hours, data shows that with the GenFree cabin using no fuel to power to electrical operations of their cabin and only a very small amount in the ultra-low consumption heating system, Balfour Beatty saved at least 240 litres of fuel and avoided 614kg of CO2 emissions during the 33 day period.

With a current HVO biofuel cost of £2.15 per litre, this fuel reduction produces a weekly financial saving of £129. On top of this, using Deep Green welfare also reduces toilet servicing and generator servicing costs – a weekly average saving in a twin toilet 12ft cabin of £87.50. This means using a Deep Green GenFree cabin on site in place of a standard ‘eco’ unit will benefit Balfour Beatty with a total weekly saving of at least £216.50, even before taking into account the heavier than usual occupancy of this cabin.

However, if you consider that the actual cabin occupancy of the Balfour Beatty cabin was more than 4x greater than standard at 17.5 hours average per day, and that at this time of year, cabin users would usually be running a generator-powered heater, we estimate the actual fuel saving per week could have reached 240 litres or £516 in cost terms. Add in the toilet/generator service savings, that makes a total weekly overall operational cost saving of £603.50 compared to a standard ‘eco’ cabin, and a saving for the total period of £2845.

In addition, removing the generator from a welfare cabin has the following positive benefits for the user/owner:

  • Removes the need to regularly attend the unit to service the engine (5.2 times a year for a 12ft cabin)
  • Removes all generator noise, making the cabins 100% silent in operation and a quiet restful place to work and relax
  • Removes all generator-related on-site emissions. With only a low-consumption heater using fuel, the majority of CO2, particulate matter and other harmful emissions are avoided.
  • Elimination of all generator-related outages and breakdowns. In welfare units, statistically most repair callouts are for generator issues and therefore these are avoided.

At the conclusion of the trial period, Daniel Guider, Site Engineer at Balfour Beatty, commented:

“After our trial of the Deep Green GenFree welfare unit, myself and others on the project are very impressed with how the cabin performed – it’s a really good product. The cabin was used heavily 24 hours a day, 7 days a week on the site with no issues at all. Also, the reporting to highlight the cost savings was a real eye opener – it was great to see how much fuel use and emissions we’d avoided over the period.”

“We were also really surprised with how simple the welfare units were to operate and how problem-free they were. We are used to having cabins with generators on site and to be honest, that’s where all our breakdowns occur – the generator is a real weak point, causing a lot of costly service visits to site to get them fixed. So having a cabin without a generator on site would remove a lot of issues for us.

“The whole team were really pleased with the generator-free cabins and based on what I’ve seen so far, I’d be very keen to roll them out across all our sites. I’d have them all day long!”James Kearsey, Managing Director of Boss Cabins, stated:

“We are delighted that Balfour Beatty gave our GenFree welfare such a harsh intensive trial and that the generator-free unit was more than able to prove itself up to the job required.

“I think it’s fair to say that the unit took a real hammering in terms of almost constant occupancy and yet has performed flawlessly throughout, giving Balfour Beatty’s operators a silent and comfortable welfare experience while reducing Balfour Beatty’s running costs and cutting their on-site carbon footprint significantly.”


Balfour Beatty is a leading international infrastructure group. Balfour Beatty teams operate across the full infrastructure life cycle, combining world-class investments capability and leading construction and support services to deliver large, nationally critical complex infrastructure through to local and regional projects right at the heart of local communities.

Balfour Beatty prides itself on being a responsible, sustainable business. Their Sustainability Strategy embodies their ambition to go further to reduce their environmental footprint and to have a positive, sustainable impact wherever they work.

Balfour Beatty has set out its ambition to go Beyond Net Zero Carbon by 2040.

According to their website, they are taking action to reduce the net carbon emissions of our direct and indirect operations to zero by 2040, by continuing to implement the Institute of Environmental Management and Assessment’s (IEMA) Greenhouse Gas Management Hierarchy.

Balfour Beatty are collaborating with their supply chain partners and aiming for all products and materials they procure to be net zero carbon by 2040, including developing new solutions and technologies to drive net zero outcomes for their customers by collaborating across the value chain, and decarbonising Balfour Beatty’s plant and fleet, including switching from diesel to electric, hybrid or hydrogen powered solutions.


Over the past two years, UK manufacturer Boss Cabins has been helping sites to go carbon-free with their patented Deep Green 2030 range of welfare cabins and portable toilets, proven to operate almost entirely from solar energy, slashing fuel use and producing virtually zero emissions. Also incorporating rain harvesting and water recycling and vastly reducing the need to visit site to service the cabins, the Deep Green range has had its carbon savings verified by respected independent industry watchdog Carbon Footprint. Deep Green welfare has also been shortlisted for two prestigious sustainability awards – edie’s ‘Net Zero Product of the Year’ and ‘Product Innovation of the Year’, selected as finalist (via our customer ECOHire) for the HAE’s Hire Industry Product of the Year’ and Highly Commended in the Showman’s Show Green Supplier and Innovation Award.

Now after 24 months of data proving how successfully Deep Green units reduce fuel use and emissions on site, Boss Cabins have taken their solar innovation one step further with the launch of the patent-pending GenFree range. This 100% silent running welfare cabin range is the world’s first towable welfare range with no on-board generator at all. With all electrical power supplied by an advanced solar system with extendable arrays and vertical panels, this breakthrough in site welfare is available for demo now.

The Deep Green GenFree range has also been shortlisted for the following awards: Plantworx Innovation Awards 2023 – Environmental Initiative category; Construction News Awards 2023 – ‘Best Product Innovation’; Ground Engineering Awards 2023 – ‘Award for Equipment Innovation’

For more information, contact the Boss Sustainable Welfare Team on 01778 300475.

Download the case study report by clicking here.

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      How we handle your data

      Details which you provide here will not be shared with anyone outside of Boss Cabins and will be kept in a safe and secure location. You may request your personal data to be removed at any time.

      We may obtain data from carefully selected third parties, including our clients. For more information read our privacy policy.