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Scottish National Portrait Gallery, Edinburgh

Scottish National Portrait Gallery, Edinburgh

Acclaimed refurbishment project with better than expected energy savings

Overview

This highly acclaimed refurbishment project was the 2013 winner of the Carbon Trust Scotland's Low Carbon Building Award Refurbishment Category. It has seen better than expected energy savings since its completion in 2011, and the project has set a benchmark for upgrading other galleries in Scotland and further afield.

The project, valued at £17.6m, involved the reconciliation of sub-divided spaces back into one gallery. The 'A' listed gothic facade could not be altered, but internally, work was undertaken to ensure the building meets modern sustainability requirements.

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Image: Gothic Facade © Page/Park

Approach

There were a variety of different measures undertaken at the Gallery to improve the thermal performance, energy efficiency and occupant experience. The refurbishment included an element of conservation, as well as energy retrofit. Two issues were seen as a priority, the freeing up of gallery space from support functions and circulation. Few visitors had previously made it to the top floor of the gallery.

 

Fabric

As the exterior 'A' listed facade could not be altered, internally a great deal of work was done to improve the building fabric. The existing structure was exposed where possible, providing thermal mass to help control temperatures. Unnecessary partitions and surface finishes were removed to return the building to how it was originally intended to be.

Original roof lights were restored, with double glazed, low-e glazing units and solar shading, where required. Natural light was further increased by the restoration of existing windows which had been painted over or covered up. Secondary double glazing was installed on the large Gothic style windows, to maintain the aesthetics and improve thermal performance.

Insulation was installed where ever possible, including in the replaced roof structure.

Services

The ageing existing services had to be replaced with modern equipment that was capable of maintaining the required internal environmental conditions. Thermal models were produced to explore various service and fabric interventions.

Temperature, and humidity in particular, must remain within strict limits to ensure no damage is done to the historic art collections. BS 5454 sets limits for galleries (19°C ±1°C, RH 50% ±5%) but these were extended slightly to 18-23°C and RH 40-65% to allow energy to be conserved, along with the paintings.

Highly efficient services were specified as the historic nature of the building and local planning constraints ruled out the use of renewable technologies.

Four gas-fired condensing boilers (approx. 94% efficiency) provide heating and run an air handling unit for ventilation. A 195kW cooler maintains ambient temperatures and 14 air handling units were also installed, those in non-gallery spaces include heat recovery systems. 

While natural light was maximised, electric lighting was also necessary. LED lighting was used throughout to reduce energy consumption by 62% and also to reduce heat output. The majority of the Gallery (95%) includes dimmer controls.

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Image: Top Lit Gallery Spaces © Page/Park

Space and Layout

New mezzanine levels were installed to provide 40% more hanging space without adding to the service requirements or overall building footprint. Below the new mezzanines, education and visitor facilities have been located.

New openings were created to either side of the entrance to provide a range of options for the visitor. A large, glass lift was installed in the east end to provide access to the upper floors.

The library was carefully dismantled and relocated, to create an enfilade of top-lit gallery spaces on the top floor.

Performance

With these measures in place, the National Portrait Gallery of Scotland uses up to 42% less energy than a gallery run strictly to the BS 5454 standards, equivalent to 14% reduction in CO2 emissions for the complete building.

Originally 50 lux was specified for the electric lighting throughout the gallery spaces, but this was relaxed to 35 lux to further reduce energy consumption. Interestingly, visitors have commented favourably on the lighting despite this.

 

Justin Fenton, of Page/Park Architects, said of the project:

“Successfully achieving a low carbon restoration of this historic building has been focused by the Carbon Trust’s guidelines which set the standards for sustainable design.”

Lessons

"The Scottish National Portrait Gallery has now been open to the public for one year so we have experienced most weather conditions. The governing principle of allowing the temperature and humidity to drift gradually in tune with the inertia provided by the solidity of the building, without the plant reacting continuously or violently, has been very successful."

Robert Galbraith
Strategy & Projects Manager, National Galleries of Scotland

 

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Image: New Mezzanines and Glass Lift © Page/Park

Links

Scottish National Portrait Gallery

Page/Park Architects

Carbon Trust

 

 

Resource Efficient Scotland supported the preparation and presentation of this case study for the Retrofit Scotland website.

 

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