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Land, Sea & Islands Centre; Arisaig

Land, Sea & Islands Centre; Arisaig

An energy efficient upgrade to a 19th century, stone construction visitor centre which was suffering extensive heat losses.

Overview

The Land, Sea and Islands Centre (LSIC) is an extended 19th century stone building, owned and operated by the Arisaig Community Trust. Its principal use is as a heritage and visitor information centre, displaying historical and contemporary exhibits from the local area. It is also used for a variety of community events.

The LSIC was extended and refurbished around 1999 but continued to suffer excessive heat loss and draughts. This affected the thermal comfort of the building’s users, resulted in high on-going running costs and the resulting operational carbon dioxide (CO2) emissions.

Sam Foster Architects were commissioned by the Arisaig Community Trust to prepare designs and specifications for the energy efficient upgrade of the LSIC building. This was funded with the help of £100,000 from the Climate Challenge Fund. The main focus was for the building’s energy consumption to be reduced to deliver a 75% saving in operational CO2 emissions.

The main challenge for the architects was the lack of information on the existing building construction, required to quantify heat loss through the opaque building elements and to assess the internal environmental conditions. The CCF funding application specifically targeted a considerable reduction in CO2 emissions, so a building assessment was required to help inform design decisions. A study to assess the energy consumption, fabric heat loss, internal thermal conditions and the user engagement was undertaken to assist SFA with design work.

Building Performance Evaluation (BPE) undertaken by MEARU both before and after the latest refurbishment. These quantified successful reductions in air permeability, heat loss, CO2 emissions and electricity use. Improvements in building user satisfaction were also recorded.

 

LSIC interior

Approach

Prior to the refurbishment work, Arisaig Community Trust were unable to keep the building open during the winter due to the very low internal temperatures. As well as reducing potential income generation for the Trust, volunteers and visitors complained of high levels of discomfort and the artifacts on display were at risk of degradation by dampness.

The Trust’s electricity cost over twelve months (which covered electric night storage heaters, lighting and small power usage) amounted to over £2,500. This was a significant and unsustainable financial burden for such a small organization.

Following the architects’ work in the area on similar energy efficiency projects the Trust approached SFA to help prepare a building warrant application, and then funding application, for improvement works to the building. SFA’s standard approach to the refurbishment of traditional buildings is to firstly understand their construction and then utilise appropriate, compatible and non-toxic building materials and construction techniques to ensure that the completed work is of the highest quality and robustness.

Previous Refurbishment

During the 1999 refurbishment the original building had been fitted with a timber frame inside the stone walls. The walls and new timber trusses were insulated with flexible glasswool. These were then lined with a polythene vapour barrier and plasterboard, and tongued-and-grooved timber linings. A concrete slab replaced the original earth floor of the existing building. Timber windows were fitted in original and new openings in the stonework. One of the external stone walls had been left exposed as a feature, with a cement render applied externally to the rest of the original stonework.

The 1999 extensions to the building comprised 100mm insulated timber frames with insulated trusses and an external leaf of cement-rendered blockwork. Halogen lighting and inefficient electric storage heaters had been installed, together with a toilet.

This work failed to significantly improve the thermal performance of the building, resulting in high running costs, discomfort for volunteers and visitors and the need to close during the coldest months.

SFA Refurbishment

A short term BPE study undertaken on the 1999 refurbishment building recorded the electrical consumption and building fabric performance. These data were used to optimise the technical proposals for SFA’s refurbishment work.

SFA developed a specification that removed the plastic vapour barrier and retained and replaced as much of the existing insulation as possible before adding a continuous layer of rigid, tongued and grooved woodfibre insulation internally to the external walls and roof. The exposed stone wall received a coat of lime plaster and woodfibre insulation.

The existing floor tiles were removed from the concrete slab and an ultra-high performance aerogel insulation blanket fitted to reduce heat loss. Wall insulation was tightly butted against, and taped to, the floor insulation to minimise heat loss at these potential weak spots. An air permeability target of 3m3/hr/m2 @ 50Pa was set for the refurbished building.

All windows were replaced with high performance triple-glazed timber framed units, complete with easy-to-operate handles and trickle-vents to ensure adequate ventilation of the building throughout the year.

The wall and roof insulation was fitted extremely carefully, and then sealed to windows and doors with airtightness tape, to minimise the extent of draughts and corresponding heat loss.

Fermacell – a very strong board made from cellulose and gypsum – was fitted to the walls and roof and a floor finish of linoleum sheet laid throughout the building. The Fermacell linings were then painted with natural, non-toxic paints from Auro.

As well as minimising off-gassing of toxic chemicals through selection of non-toxic materials and finishes, the additional wall and roof insulation actively buffer internal humidity levels – an important function considering that stone and paper artifacts are displayed all year round.

All artificial lighting was replaced with LED fittings and the old, inefficient storage heaters replaced with modern, more efficient units. Unsuitable building orientation for photovoltaic panels precluded their use to offset electrical demand.

To assist with handover to the building users, a Quick Start Guide was produced. This identified the key elements of the building and how to operate them, as well providing guidance on maintenance for different parts such as windows and heaters.

Performance

Pre-refurbishment Building Performance Evaluation carried out by MEARU in December 2014 was used to quantify internal environmental conditions, heat loss through different parts of the building and gather occupant satisfaction data. This established:

  • A mean air permeability of 18.03m3/hr/m2 @ 50Pa (based on the average of pressurization and depressurization results). In real terms this is extremely draughty.
  • Thermographic imaging showing areas of missing and defective insulation in the walls and roofs:

 LSIC Image 1

 

  • Poorly-installed, and poorly-performing windows.
  • Measured heat loss (u-values) significantly greater than the values they should have achieved, e.g. 0.72W/m2.K instead of 0.30W/m2.K for areas of flat ceilings.
  • Uncomfortably low internal temperatures:

 LSIC Image 2

  • High electrical consumption.
  • A lack of understanding by volunteers on how to effectively operate heaters and ventilate the building.
  • Volunteer dissatisfaction with internal temperatures.

 

Following the refurbishment work to the building MEARU carried out post-refurbishment monitoring of the same criteria in December 2015, which established:

  • Air permeability reduced by 85% to 2.70m3/hr/m2 @ 50Pa.
  • A significant reduction in areas of heat loss throughout the building: 

LSIC thermal comfort img 3

 

  • Very low heat loss around the new windows:

LSIC Thermal mapping

 

  • Up to 63% reduction in heat loss through walls and roofs.
  • 58% reduction in electrical energy use, despite the building being open for 25% longer:

 LSIC Electrical consumption img 5

  • Better understanding by volunteers of how to control openable windows and storage heaters.
  • Higher volunteer and visitor satisfaction with internal temperatures.

 

Overall, a 57% reduction in energy use and CO2 emissions was recorded.

Lessons

To minimise costs to the clients, the architects were not involved on site but prepared detailed drawings and specifications setting out clearly the construction strategy and detailing at all interfaces. A local builder was tasked with carrying out the refurbishment in the knowledge that the workmanship would be evaluated and tested at the end. Although it was a risky strategy to not have any site inspections, happily the gamble paid off and levels of workmanship were adequately high.

Having a firm understanding of the thermal performance and internal environmental conditions of the existing building, as well as building user feedback, formed an intrinsic part of developing an appropriate refurbishment strategy for the building.

The post-refurbishment monitoring results coupled with the feedback provided the architects, the client and the Climate Challenge Fund (who funded the majority of the work) with a clear understanding of the quantitative and qualitative improvements that were achieved

The benefits of pre- and post-refurbishment measurement are clear, but would not have been possible on this project without the encouragement and support of the client, Arisaig Community Trust, or the financial support from Interface and Zero Waste Scotland.

The extent of knowledge and expertise from MEARU, as well as their lucid reporting methodology, makes clear the skill required in monitoring buildings well but raises larger questions of how such testing can become routine on all building refurbishment projects in the future.

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