22 Observatory Road:

Zone Architects

ZONE Architects worked with owner/developer Julia Bouvy and her family to help realise her ambition to build a family home on a spectacular site towards the top of Edinburgh’s Blackford Hill, enjoying panoramic views over the city.

Materials

Replacing a tired and inward-looking bungalow, the decision was made to use timber in the construction of the new house as far as possible in order to reduce its carbon footprint.  The three-storey house – featuring living spaces to the top floor, bedroom accommodation to the middle floor and the lower level occupied by a separate granny flat – was built using a Cross Laminated Timber (CLT) primary structure.

This CLT shell was designed and installed by Spanish company Egoin and erected in a week.

Low Carbon Design

The zero-carbon building was designed to passive house standards with 0.1 u-values, incorporating very high levels of airtightness combined with MVHR, solar hot water and PV. Internally the slabs of timber have been deliberately left uncovered in order to create a natural ambience to the interiors as well as showing off the structural capabilities of the timber.  The ambition was also to make the air quality in the house as healthy as possible using natural materials, and as a result, the potential for toxins has been minimised by the use of natural additive-free wood fibre insulation which was chosen to wrap the CLT structure, creating a breathable outer wall construction.

Design

22 Observatory Road references the 1894 Observatory Tower at the top of Blackford Hill, with its sandstone base safeguarding the mechanics of the copper-clad telescope covers, in that the house is sandstone clad to the street’s route up the hill, effectively protecting a series of timber and zinc-clad inner areas which contain the intricately connected interior spaces.  Elsewhere the main cladding material used is Siberian larch, detailed with a deep rib effect and vertical cantilever to form the balcony balustrade.

The project demonstrates that the rigorous process of decision-making that was employed throughout the whole design and build ensured that the most ecological choices were made.

Images: C Humphreys