Generate electricity and heat by installing solar PV and other technologies


Save energy by advising on the most appropriate energy efficiency measures


Build or renovate your home or workplace to low energy/passivhaus standards




Solar photovoltaic (PV) –  can either replace or supplement your existing electricity supply. It is different from solar thermal, which uses the sun’s rays to heat water.

At home, the size of the system is unlikely to be large enough to generate electricity for all your needs, especially at night when there is no light, which means that you’ll still be connected to the grid.

A solar electric system consists of solar panels (to create electricity) and an inverter (to convert that electricity into a form which can be used at home). The panels can be fitted onto your roof or placed in any other unshaded area.

What’s so great about solar electric?

  • Generates free electricity to power your appliances
  • Saves you money – a typical domestic system provides c. 50% of your electricity needs
  • Makes you money – the ‘Clean Energy Cashback’ scheme will pay you for every unit of solar electricity you create over the next 25 years (click here for more info)
  • Protects you against rising energy bills
  • Gives you greater energy independence
  • Can increase the value of your home
  • Easy to install
  • Requires little maintenance – generally limited to hosing / dusting them every year



We provide three types of consultancy:

  • Full Energy Design
  • Energy Survey
  • Bespoke Energy Advice

It may not be glamorous, but at greentomatoenergy we believe in applying the laws of physics to low energy building. In order to mitigate against the risks of low energy building (primarily performance, cost and fabric), our team of engineers will apply real science to your project. This will give you the confidence that the work you are doing will deliver lasting results.

We are an independent consultancy that will propose the most appropriate solutions, helping you to avoid the minefield of technology-specific salespeople.

We work with builders, architects, designers and self-builders to ensure that the most practical, affordable and efficient renewable and energy-saving measures are selected for each project. We will provide support through each step of the build process.

The government recently released the Green Deal consultancy. Our briefing note can be found here. For all the details, visit the DECC website.



In low energy buildings one of the hardest elements to get right are the windows. Not only can it be a struggle to find windows with low enough U values but they can also be a real problem when it comes to air tightness. In addition to the associated design issues it is the windows which often hold a project up with suppliers failing to deliver within the agreed lead times. These problems can be particularly hard to solve when retrofitting a period property with sash windows.

These were just the problems greentomatoenergy faced when retrofitting Lena Gardens to Passivhaus standard. With no ready option available the team set to designing a window which could both provide the thermal performance we required and retain the traditional sash appearance. The result was our very own triple glazed sash look alike window.

Such was the success of the windows we have since stared manufacturing the windows for all. So why do we think our windows are so great?

  1. Thermal Performance – the windows have a whole frame U value of 0.749
  2. With a fixed top sash, three seals around the lower sash and a tilt and turn mechanism they are far more airtight than a sliding sash.
  3. The tight seals and triple glazing give a far greater degree of sound insulation
  4. They are less expensive to maintain than sliding sash windows with no requirement to periodically replace cords


greentomatoenergy wants to change the way you think about energy


The world is changing. We are moving from the Industrial Age to the Clean Energy Age, a new period in which we will use less energy, more efficiently.  The energy that we do use will be clean, renewable and most likely generated and delivered by a much more decentralised structure.

We design, supply and install renewable energy technologies and are specialists in low energy and passivhaus building. With a focus on offering outstanding personalised service, we deliver high quality, low- and zero-energy solutions for all types and sizes of projects.

We have a network of highly experienced installers and builders and because we are not tied to any single manufacturer or technology, the solutions we recommend are the most appropriate for your project and budget.