Passivhaus Affiliate

Big up for Buccleuch Street!

Midlothian Council's first Passivhaus project is nearing completion. The Buccleuch Street project in Dalkeith was the first Passivhaus scheme undertaken by all the project team, with the exception of its Passivhaus Designer and Passivhaus Certifier. 

Buccleuch Street Dalkeith Midlothian Council. Image credit: Smith Scott Mullan Associates

Midlothian Council has made a strong commitment that all new social housing be Passivhaus standard and has set this out in its housing design guide.  Midlothian Council worked closedly with PHT members Smith Scott Mullan Associates (SSM) to develop the guide, following an initial proposal and feasibility study undertaken by SSM.  

Buccleuch Street will be the first project delivered as part of this commitment. The project involved the construction of new block of flats aiming for the Passivhaus standard alongside the (non-certified) refurbishment of a nearby historical building. The site was very constrained, as well as overshadowed, and yet the team were able to achieve Passivhaus requirements with the design. The design combines the low operational carbon of the Passivhaus standard, with solar photovoltaics, heat storage and electric heating. 

Key stats

  • Construction: Timber frame I-joist

  • Number of homes: 6

  • TFA:  369.6 m2 

  • Form factor: 2.38

  • Completed: October, 2023

  • Certified: Aiming for Passivhaus

Buccleuch Street Dalkeith. Image credit: Smith Scott Mullan Associates


These flats are going to be great homes for folk right in the centre of historic Dalkeith, but more than that this is a super energy efficient project and a great chance for the council to learn about building houses for the future.

Stuart McKenzie, Cabinet Minister for Housing, Midlothian Council


Overall U-values 

Buccleuch Street Dalkeith. Image credit: Smith Scott Mullan

Floor: 0.072 W/m2K                             

Concrete slab

Wall: 0.123 W/m2K

Timber frame I-joist with brick/ zinc cladding .

Roof: 0.060 W/m2K

Pitched roof

The decision to adopt the Passivhaus standard on this development was made with a view to helping Midlothian council meet their wider net zero targets, as well as helping them tackle the issue of fuel poverty whilst providing comfortable housing for their tenants.

Jarek Gasiorek, Associate and Architect, Smith Scott Mullan Associates


Building performance 

Designed energy performance 


Heating Load (≤ 10 W/m²)


8.7 W/m²


Primary Energy Renewable (PER) Demand (≤ 60 kWh/m².a*)    


82.9 kWh/m².a


Primary Energy Renewable Generation


31.9 kWh/m².a


*+/-15 kWh/m².a allowance if offset by energy generation. See Passivhaus criteria


Challenges & lessons learned

The staircase for the project proved to be one of the most challenging aspects of the design, with the need for fire protection, structural stability and housing the MVHR all creating competing demands. To address fire safety the stairs were concrete and built on steel. The MVHR systems for the flats were located within the staircase ceilings and so will be easy for the maintenance teams to access. However, fire regulations meant that additional measures were needed around the MVHR ducts leading from the staircase to the flats. 

The project was the first experience of Passivhaus for many of the project team and inevitably it has been a steep learning curve. However the fact the scheme has been running concurrently with the Burnbrae Passivhaus development for Midlothian has meant that the team has been able to transfer lessons learned between the two projects. The use of the I-joist timber kit external wall build-up was one of the positive lessons than will be taken forward into other projects. The use of I-joists simplified construction as the thickness of the I-joists meant that all insulation could be contained within the structure and no additional insulation was needed to be added or sandwiched in. 

Key team 

Buccleuch Street Dalkeith. Image credit: Midlothian Council


Visit the project

Attendees of the UK Passivhaus Conference 2023 will have the opportunity to visit the Buccleuch Street project as part of our Midlothian social housing tour. Book your place today!

Passivhaus site tours at UK Passivhaus conference 2023

You may also like 

Passivhaus social housing
How to build a Passivhaus
An introduction to Passivhaus - FREE course


Further information 

Buccleugh Street, Dalkeith

Passivhaus Social

Passivhaus Benefits Guide & costs research 

UK Passivhaus Conference 2023: Site tours

Previous PHT Story: Bonny Burnbrae - 1 August 2023

Previous PHT Story:Midlothian Council walks the walk - 29 June 2022

1st August 2023

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