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Kilmelford Church, Argyll and Bute

Kilmelford Church, Argyll and Bute

Trial heating improvements, using radiant heating panels

Overview

Kilmelford Church was built in 1785 and renovated in 1890. It is a small rectangular building, Category C Listed, of whinstone rubble construction with sandstone dressings. The roof is pitched and of west highland slate. There is a small vestry wing to the south. Two lancet windows sit on each side of the nave, and two on the east and west ends, with a high level wheel window on the west gable. Original stained and shellac finished pews line the nave, and there is a mezzanine level at the West end which provides extra seating.

This case study covers work to improve the thermal comfort of the church, through upgrades to the heating systems, and the use of new technologies. However, a wider programme was undertaken in the years before this work, between 2008 and 2010, to repair the building fabric, and reverse extensive water ingress and damage. This repair programme included work to the roof, repointing, masonry repairs and repairs to the leaded windows. Much of this included reversing unsympathetic repairs made earlier, including the use of inappropriate materials such as cement pointing and oil based paints on plaster. The West gable which was particularly wet, was repointed with lime mortar in 2009. This, along with stone and roof repairs made an improvement to the internal conditions as the walls dried out. The service upgrades would have been pointless without first repairing and improving the building fabric.

A significant contributing factor to the poor thermal comfort of the church, is its exposed location – 700 metres from the sea. The position of the main entrance also results in large draughts, allowing heat to be lost from the building.

Kilm

Kilmelford Church © Historic Scotland

 

Approach

The aim of this pilot was outlined by the two partners in the project, The Kirk Session and Historic Scotland:

  • To establish and understand the existing electricity consumption of the church building
  • To design and assess the effectiveness of a new radiant heating system
  • To procure and install the selected system and evaluate it
  • To develop alternative options for background low level heating to preserve the fabric
  • To reconfigure the electricity distribution to accommodate future needs, including potential use of renewables.

 

The work undertaken in this case study follows on from work Historic Scotland conducted on the use of radiant heat in a domestic property (see Historic Scotland Technical Paper 14 on the left), where the aim was to heat the contents and internal fabric of the property, rather than the air itself.

The existing heating system in Kilmelford Church consisted of ‘greenhouse heater’ style electric tubes located under each pew, plus four wall mounted domestic electric convectors. These were expensive to run, yet did not provide sufficient heat for the parishioners. The system required long periods of pre-heating, yet the inside of the church was damp and frequently cold.  

Radiant heat delivers thermal comfort due to the infra-red beam from the heater warming the object in front of it, rather than the air in between. This can be beneficial in buildings where it is difficult to achieve air tightness.

An M&E contractor was appointed by the Kirk Session to investigate different heating systems. A range of options were selected for trial, and were installed in September 2013. Over the winter of 2013 / 2014, the parishioners were able to test the different options and feedback. The different options were:

  • Heated seat and seat back cushions – trialled on a single pew
  • Radiant panel heaters in front of a pew
  • Radiant panel heater mounted under the mezzanine soffit
  • Long wave radiant heaters mounted at high and low level in the chancel.

 

There was also consideration of the need for background heating, to keep the air and fabric dry. An Air Source Heat Pump (ASHP) was selected to give low level heat (16°C) for short periods each day. The electrical distribution boards were also reconfigured to allow for the use of solar panels in the future.

The selected options, installed in summer 2014 by a local contractor, were:

  • Two wallhead level radiant panels mounted at the base of the roof
  • Radiant panels mounted on the back of the front ten pews
  • Radiant panels mounted on the underside of the mezzanine
  • ASHP (indoor fan unit at the top of the stairs, external unit on NW corner where it was felt to be least visible).

 

The heated cushions were not chosen as the parishioners became too warm, and low level wall mounted radiant heaters were felt to be ineffective.

Performance

The total cost of the interventions was £29,127 (including VAT). An application has been made to the Listed Places of Worship Grant Scheme for the reimbursement of VAT paid.

The heating system controls were set so that the radiant panels and heaters would come on automatically one hour before church events. The ASHP was set to come on for two hours each morning to ‘pre-warm’ the church, and to maintain a background temperature of around 16°C. The existing convective heating system was also retained for use during church services to combat cold draughts.

The temperature in the church improved dramatically, and most parishioners were very pleased. The panels on the underside of the mezzanine were particularly effective at conveying a sense of warmth on entering the church.

Energy consumption and fuel costs also reduced. Pre- and post-intervention consumption was monitored. Consumption has reduced from an average of 4,674.25kWh/yr to 3,185kWh/yr, and was significantly lower when compared to similar Scottish churches. Monitoring will continue, but energy savings of around £250 per year have been realised, along with a huge improvement to thermal comfort.

Lessons

The congregation had long been dissatisfied with the existing heating system, and energy costs had been a financial burden for the congregation. The heating upgrades have improved the thermal comfort for users and will maintain the building fabric also. The damp smell has gone and the condition of hymn books and other contents have improved. The interventions have generated hope for the future use of this community asset.

While the work was costly, the payback times are not thought to be excessive, and the congregation intend to investigate the use of renewable technologies to further carbon and financial savings.

However, the system requires maintenance and an understanding of its operation. The timings of the radiant panels and ASHP may need to be amended for the summer and winter months – and all are controlled separately. The continued background warmth provided by the ASHP is critical for the success of the radiant heating (which require the background heating to work effectively) and for the continued maintenance and the drying of the building fabric. In a period while the fabric convenor was on holiday, a member of the congregation switched all the electric supplies off ‘to be sure’ for two weeks, and the subsequent re-warming of the interior took several days.

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