Client:  Holdhurst Farm Estate, Surrey. 

7-bedroom house, visitor cottages, commercial units, stables and equestrian unit, indoor and outdoor swimming pools and a pheasant shoot.


The number one priority for Optima BES in looking after Holdhurst Farm Estate in Surrey was to meet the complex heating needs of a luxurious visitor centre, for all year round use. In addition, the brief was to lower the carbon footprint AND earn income from heat generation, taking advantage of government financial incentives.

Optima BES offered an independent analysis of proposals from a range of suppliers, weighing the pros and cons from financial to logistical, even minimising any physical impact of the scheme.

Optima BES took the challenge head on:

  • Countering a previous firm’s advice for ground source heat pumps with a stronger proposal for biomass; this was cheaper to install, it used the farm estate’s supply of woodchip (to provide up to 40% of fuel locally) and gave an excellent payback of around 6 years with continuous, guaranteed income for 20 years.
  • Closely investigating the size of the installation, initial cost and Return on Investment (of 10% pa) to secure the strongest possible revenue.
  • Working closely with main contractors, we pushed the build through on a rapid schedule to meet deadlines for maximum Government Renewable Heat Incentive (RHI.)
  • Obtaining relevant planning authority permissions for the work and reconfiguring the scheme, re-siting the boiler-room housing in an existing building to reduce costs and speed up the build.
  • Our advisors also found specialist suppliers for a low-maintenance, 200 Kw HDG Biomass boiler with a gas-fired back up, to ensure a robust supply of heat. An emergency electric generator guarantees critical power for drainage pumps, lighting and more.


The project

Ground source heat pumps advised by a previous bidder would have needed to be installed at very deep levels, causing a high cost base, possible delays in operation (which may have meant missing the maximum RHI payments available) and potential disruption to the smooth workings of the estate.

By contrast, biomass was available on site and offered a very clean looking installation to ensure a welcoming aspect for visitors, with no boilers, flues or flumes in evidence. Burning wood is a low CO2 method of heat production, qualifying for excellent Government RHI incentives. There are continuous loads on the system, even during the Summer months, and this ensures constant revenue from the central plant.

We believe biomass to be ideal for farms and businesses such as Holdhurst, that use large amounts of heating and hot water, as they generate heat cheaply and effectively from sustainable wood – in this estate a high percentage of chip could be sourced locally. This is a long-term solution, avoiding reliance on expensive oil or LPG gas for the foreseeable future – as well as attracting a 20-year government-backed financial incentive.


The task:

  • There was a tight time challenge to meet government deadlines and secure the highest rate of RHI.
  • The system had several aesthetic considerations to blend in with an elegant rural setting.
  • Fail-safe operations were essential; high-end customers have exacting standards and expect excellent warmth and no loss of amenity.

Space on such a large estate is not at a premium but the initial height of the proposed boiler room would have added significant cost and delays, which did not make financial sense. To avoid these concerns and possible planning constraints, we worked with multi-disciplinary contractors, TH White, to re-site the plant in an existing building. Biomass is a very natural and direct heat source, ideal use of an existing farmland resource. Low maintenance is a plus; ash bins need to be emptied rarely and there are no other ongoing concerns.

This form of heating is also highly efficient where buildings require warmth early and for long periods of the day.