Independent Renewable Energy
Case Study - Stourhead House Client: The National Trust
Stourhead is a large Palladian house with a famous landscape garden. It is home to a substantial collection of artefacts accumulated over many generations by the Hoare banking family . A large part of the house is open to visitors but there are also a number of occupied flats and a suite of NT offices. Two oil boilers in the basement supplied heat to the house via a range of pipework radiators of mixed age. In common with many NT properties the heating within much of the house is used to control relative humidity so as to preserve the fabric of the building and protect the artefacts.
Redcotec's involvement at Stourhead was in three phases:
Phase 1: An options appraisal for renewable energy heating. This began with a survey of the existing heating system and determination of the required heating capacities in each room to meet either the relative humidity or comfort heating needs. The appraisal included consideration of the environmental impact (in terms of carbon emissions), the financial case, the historic nature of the building and the feasibility of installation within the available space. Redcotec provided advice and guidance to the property team so that an informed choice of heat source could be selected.
A biomass wood chip boiler was chosen for a number of reasons: excellent performance in the reduction of greenhouse gas emissions, the ability of the NT to provide wood chip from its own estate, a suitable plant room in the form of a disused Victorian pump house, maximisation of heat output from the low powered heating circuits and an attractive financial case linked to the RHI.
Phase 2: Redcotec provided drawings and detailed information to assist to the NT with successful applications for planning and listed building consent. A performance specification was produced that included a series of commissioning processes and tests, this was included in the tender pack for prospective contractors. Redcotec provided a tender review report to the NT and took part in the contractor selection process, providing technical and best practice advice to the selection panel. On appointment of the contractor we worked with them to develop the final design. This arrangement allows the contractor to work with their preferred equipment and methods and yet maximises the performance and reliability of the finished installation.
Phase 3: Redcotec acted for the NT as client's engineers throughout the installation ensuring that the design was properly implemented within the circumstances of a historic listed building. Redcotec attended site to inspect the work at key milestones attended fortnightly project meetings. A 130kW and a 90kWkW rather than a single 250kW wood chip boiler were installed to provide security of heat supply and maximise the seasonal efficiency. The boilers were installed in a Victorian pump house with a new chip store and fast auger loading bay. A 180m buried heat main connected the new boiler house to the mansion boiler room. The heat main was installed by a combination of trenching and directional drilling. The work in the boiler room included a plate heat exchanger to provide hydraulic separation between the mansion heating and new boilers. A bespoke control system was put in place to integrate the new boilers with the mansion heating system in a manner that maximised the performance of the boilers.
Conclusion: Successful commissioning of the scheme was witnessed by Redcotec personnel. All the performance tests included in the original performance specification were met. The oil boilers and tank were removed from the mansion with the added benefit that the rooms directly above the mansion boiler room no longer suffer from overheating. The scheme was successfully accredited for the RHI and will reduce carbon dioxide emissions by around 72 tonnes per year.