Kilmartin Glen used to be very busy and it has the architecture to prove it. Hundreds of ancient monuments survive from the Neolithic and Bronze ages up to 5,000 years ago. Rock art and standing stones are common in western Argyll valley, while a linear cemetery of five burial cairns, each with a central chamber, stretches for over a kilometre.Things have slowed down recently, though. In the last handful of centuries the glen has been a sparsely populated agricultural place. The village of Kilmartin is formed of a few dozen homes, with a 19th-century church and manse atop a bank on its western edge.Since the late 1990s the white manse and its steading a long stable and outbuilding have been the home of Kilmartin Museum. The small centre celebrates local pre-history and displays treasures excavated in the glen. But by 2012, the museums collection of around 22,000 artefacts had outgrown its lodgings and a competition was launched for expansion.AdvertisementIt must have sounded like a plum job when Reiach and Hall Architects won it in 2013 but it came with difficulties. New exhibition and archive space had to meet stringent museum standards while also withstanding decades of ruthless Highland weather. Moreover, money was very limited and the project dragged on. Planning was secured in 2018 while construction started in 2021, completing in 2023. One suspects Reiach and Hall, based an 141-mile drive away in Edinburgh, didnt earn much from the job.Its a small museum in a remote area that really relied on the funding streams, explains Libby Heathcote, the last of four project architects on the scheme. We were part of that fundraising journey and thats what people forget: the actual designing and building is a relatively short part of the entire process.Eventually 12 funding streams were secured from various charities, governments and agencies, with more raised through private donation supporting the total build cost of 4 million, equivalent to 3,000 per m2.The design was led by the practices director and chairman Neil Gillespie, and his first decision was to keep the manse and steading. This ticked budget and sustainability boxes, but Gillespie also saw the manse as a symbolic thing, which already had a presence.The original design fully wrapped the manse in a two-storey extension with one storey built down into the side of the bank. The manse became akin to a central burial chamber, with the referential extension like the outer parts of a burial cairn.AdvertisementAs budget realities bit, however, plans were shorn in 2015. The completed building doesnt wrap around the manse to the west, but instead snakes around its other three aspects and connects to the steading.An austere faade faces east, parallel to the road from which visitors arrive. The architect had wanted it to be white brick but the client was concerned this would show the dirt so a grey brick was chosen instead. It will look better with age but, on a wet day, it already contains an array of grey tones, reminiscent of the nearby cairns. To the south, the long flank turns at an 110-degree angle 20 degrees off perpendicular, a nod to the linear cemetery being 20 degrees off north.Visitors are, however, more likely to follow the wall north from car park to entrance space. The wall cuts in and curves back to the entrance, emphasising a large circular space also bound by stone benches. The circle provides ample visitor space, its shape echoing the roundness of the burial cairns, and is repeated in a porthole by the entrance, as well as in manifestation elsewhere.Inside, the main entrance area is a long rectangular space, with a small shop (visible through the window to entice visitors) and a direct link north to the caf in the steading. The western wall is glazed with regularly spaced louvres and, according to a museum worker, on a sunny day the shadows look like standing stones. This elevation looks smart, if quiet, from the Glebe Cairn, the northern most burial cairn located down the bank to the west of the museum.The permanent collection is in the extension space to the east and south of the manse. It is strikingly dark a decision born of sympathy for the artefacts, which have been recovered from earth and graves where they had been for millennia.The concrete wall is exposed and has a similar grey texture to standing stones. The roof, meanwhile, is made of dark timber fins similar to the burned timber structures created by prehistoric locals. The space between the timber fins has black wood wool covering services, which does an impressive job acoustically. Various eerie and percussive sounds greet visitors but never become garbled. This space, as well as the brickwork outside, quotes the work of Swedish architect Sigurd Lewerentz, known for his solemn and spiritual church designs.The museum features a variety of objects, including blades, crucible fragments, marked stones, spearheads, casts, jewellery and pots. A 4,000-year-old pot is displayed by a window facing the cairn where it was found. The remains of a young woman found in a burial cairn are carefully displayed in the extra-dark south-western corner of the floor.The architects idea for a porthole in this corner, looking south down the glen, was jettisoned out of respect for the dead. This is a shame as no similar view is afforded elsewhere and, perhaps, the bones would have been better suited to the central nook, accessed through the cut-out wall of the manse. Instead, this space has a hallucinogenic video evoking Neolithic ritual life.Temporary gallery space has been created in the refurbished front rooms of the manse. This is airy and bright, in juxtaposition to the permanent collection, with white linings and ceilings and lighting from bay windows and new lamps. The lower level of the extension features a large education room with birch cupboards and linings. The space can be accessed by external stairs built into the hill, allowing it to be used by locals for community groups or accessed directly by visiting school groups, allowing hyperactive fresh-off-the-coach children to bypass the entrance area.The lower level also features new curation rooms and a large archive space, stretching north from the manse to underneath the steading. Reiach & Hall has also overhauled the steading, upgrading its toilets and adding a kitchen and servery for a caf. Beyond this it has added a covered refuge area to the north while the upper floor of the manse contains office space for museum workers. The site has been made accessible with ramping and a new lift.Gillespie says that complying with regulations set out by Museums and Galleries Scotland was really quite tough. Security concerns scuppered plans for a timber structure on the upper level and led to last-minute additions of a gate and walling between the entrance and collection. Water pipes, meanwhile, were not allowed anywhere near the subterranean archive.The museums artefacts are generally robust, meaning the few with atmospheric requirements can be controlled locally in their case. But this was still tricksy teething problems with the system once triggered an alarm in Edinburgh, with a van flying west to confiscate certain artefacts. The client risked an air-source heat pump system, which will help reduce costs and emissions but is unusual in a museum setting since its control can be variable.Given the constraints, the project has done okay at sustainability. Concrete was unavoidable for underpinning the manse and the stead during excavation and also supported a very low-tech M&E system, Gillespie says, which sees ventilation enter from louvres. The architect adds that affordable stone could not be found for the faade; and while new bricks have an upfront carbon cost, they will resist the elements better than recycled brick.As a whole, the scheme is humble, effective and deliberately a bit drab. There is a kind of sadness about the museum, Gillespie reflects. The skeleton of the woman and the sense of a landscape that must have been so much more interesting than it is now, when the fields were forests. There is something lost.Nevertheless, its an interesting museum and among the most exciting works of local architecture for millennia. It would be a shame if it didnt help the glen become busier once again.Project dataStart on siteApril 2021CompletionApril 2023Gross internal floor area1,360m2Construction cost4.1 millionConstruction cost per m2 2,989ArchitectReiach and Hall ArchitectsClientKilmartin MuseumStructural engineerDavid Narro AssociatesM&E consultantMax FordhamQuantity surveyorTurner & TownsendProject manager Sigma PMPrincipal designerAlliance CDMMain contractorTSL ContractorsCAD software used RevitLandscape architectHorner + MaclennanExhibition designStudioarcSustainability dataOn-site energy generation252,549 kWh/yr (estimated)Heating and hot water load123.8 kWh/m2/yr (measured)Operational energy172.3 kWh/m2/yr (measured)Total energy load172.3 kWh/m2/yr (measured)Carbon emissions (all)35.7 kgCO2/m2/yrAnnual mains water consumption5.5 m3/person/year (estimated)Airtightness at 50Pa5-10 m3/m2.hr (estimated)Overall thermal bridging heat transfer coefficient (Y-value)>0.15 W/m2K (estimated)Annual CO2 emissions48,524 kgCO2/yr (measured)Embodied carbon468 kgCO2e/m2 (RICS A1-A5, B1-B5, C1-C4 using FCBS tool)Whole-life carbon1,874 kgCO2e/m2 (estimated)Predicted design life 60 years