Andrew Bissell and Susan Lang-Bissell set up Sunamp in 2005 to become part of the energy transition to combat climate change. Working in collaboration with the University of Edinburgh's School of Chemistry, they have developed a thermal energy storage system using salt-based phase change materials.

Speaking from the company's base in East Lothian, Ms Lang-Bissell talks about her passion for sustainability, Sunamp's future growth plans, and why it's sometimes best to "just get on with it".

Tell us a bit about your operation?

We currently employ 80 people, mainly in Scotland but also across the UK, Europe, North America and China. Our head office is at Macmerry in East Lothian, and our factory is a few miles away in Musselburgh. We have an office in Zurich and a presence in North America, China and Italy.

What do you do?

We design and manufacture space-saving heat batteries using our proprietary Plentigrade phase change material. Our Thermino heat batteries are reliable, low-maintenance, non-toxic, and significantly smaller and more energy efficient than traditional hot water cylinders.

This year we were thrilled to be named a finalist in the Royal Academy of Engineering’s MacRobert Award alongside Google DeepMind and University of Oxford Vaccine Consortium with AstraZeneca. Last year our technology was recognised with a King’s Award for Innovation.

Who are your customers?

Sunamp is a B2B business, so we sell our Thermino heat batteries for hot water to housing associations and developers in the residential market and through our distribution partners and heating installers.

We also have a commercial and industrial division focused on developing our Central Bank range which provides thermal storage solutions up to the size of shipping containers. We currently have a project transporting heat along the Thames on barges which could eventually supply over 3,000 homes connected to a London district heating network.

How much investment has the company raised to date, and what is your latest annual turnover?

We have attracted a range of funding from a mix of government grants, venture capital, and strategic investments to support our development and expansion. In the early days grants from Innovate UK were crucial in supporting our research and development activities. Angel investors provided initial capital to develop our product and market presence and Scottish Investment Bank, the investment arm of Scottish Enterprise, has been a long-term supporter.

We completed a significant investment round in 2020, raising £6 million. A year later we raised a further £4.5m to boost our manufacturing capacity and support our international expansion plans.

Today, our turnover is around £10m and looking ahead, we will continue to leverage funding to drive growth, enhance our product offerings, and contribute to the global transition towards sustainable energy solutions. 

What led you to set up the business?

We are passionate about sustainability and set out to find innovative solutions to lower the associated carbon emissions that plague our commercial and residential buildings.

Heating and hot water accounts for over three quarters of energy use in homes, yet despite significant advancements in electric battery technology, no one had successfully developed a battery capable of efficiently storing heat. We saw a gap.

What do you least enjoy about your job, and what do you most enjoy?

I most enjoy working with lots of interesting people. We are lucky to have a very diverse staff from many different cultures. They all have such a lot to add, and we have a lot of fun. I least enjoy bureaucracy and dealing with the fallout that changes in energy policy have on our business, and on raising investment.

Our mission is to transform how heat is generated, stored and used to tackle climate change and safeguard our planet for future generations. The electrification of heating systems is paramount for greener, cleaner heat. Sunamp heat batteries and energy storage is a key component of this drive. 

We have an innovative product and need a level playing field when it comes to eligibility for incentives. It’s frustrating that even when our heat batteries are included, for example, in the Home Energy Scotland Grant and Loan, it can be short-lived.

Support was suddenly withdrawn for solar PV and energy storage systems, including electric and heat batteries. Hot water cylinders that are installed as part of a heat pump system are still funded as part of the HES Grant and Loan funding, but not heat batteries used with heat pumps which perform the same function more efficiently.  

What are your immediate goals and ambitions?

To continue our scale up. Sales growth is key to the adoption of green heating systems. Our immediate focus is on strengthening our presence in the European market, capitalising on the success we have had so far in the Chinese and North American markets, and to meet demand for our products globally.  

What would most help you achieve those goals?

Policy certainty, increasing sales and further investment to help us penetrate new markets. We have sold over 30,000 heat batteries so far, and demand is increasing as the deadline for moving away from fossil fuels approaches. Switching to renewables means householders have to find space for a bulky hot water cylinder or use a more compact solution. 

What is the most valuable lesson you have learned in business?

Be nice to people. If you smile, people will smile back. 

Where do you find yourself most at ease?

I’m at ease in most situations to be honest. Whether I'm discussing expansion plans with investors, collaborating with staff, or simply reading a book. I’m quite often out of my comfort zone, but I hide it very well. As the Chief Operations Officer, my role involves a lot of variety, and I thrive on the diverse challenges that come my way. 

If you weren’t in your current role, what job would you most fancy?

I would have loved to be a Blue Peter presenter. My background as a secondary school teacher allowed me to blend creativity with working closely with people, and I like that combination.

What is the best book you have ever read? Why is it the best?

Perfume by Patrick Suskind is the best book I have read. The unique approach of weaving a story around scent, rather than visual descriptions, was fascinating. 

What has been your most challenging moment in life or business?

Changes in policy and the uncertainty it brings for our business. 

What do you now know that you wish you had known when starting out in your career?

Don’t sweat it, just get on with it.