Pitched perfect

Conservation area aesthetic requirements resulted in a dual-faced design for the Pitched Passivhaus selfbuild in Dulwich. A contemporary elevation at the rear is combined with a traditional Arts and Crafts elevation at the front and includes a false chimney concealing the MVHR ventilation system.

House Tour: Pitched Passivhaus from RDA Architects on Vimeo.

A dilapidated 1930s house in a south London conservation area has been replaced by a newbuild Passivhaus certified home. One challenge was to meet the brief for a clean, contemporary home whilst respecting the street vernacular. The initial modern-leaning designs were met with resistance due to conservation requirements, resulting in a dual-faced design solution developed by PHT member RDA Architects. The east elevation, fronting the street, has a brick façade reflecting a traditional Arts & Crafts aesthetic, while the west elevation opens into a contemporary, open-plan designed space.

Key stats

Construction: CLT
TFA: 367 m²
Build start date: 2021
Completed: 2022
Certified: Passivhaus, 2022

Pitched Passivhaus, Dulwich. Image credit: RDA Architects

This project shows that Passivhaus’s are feasible even in the strictest of residential areas, and sets a great example for sustainable homebuilders in the future. Our biggest challenge was ensuring that the home not only met our client’s brief – a super modern, open plan Passivhaus – but met the incredibly strict parameters put in place by the Dulwich Estate. This led to some really interesting problem solving, like hiding the MVHR in the chimney and utilising a dual-faced design to sit in line with the street’s aesthetic.

Richard Dudzicki, Director, RDA Architects

Construction

The house was built using a modular, off-site Cross-Laminated Timber (CLT) system. This method offered several advantages, including precision, reduced construction waste, and minimal environmental impact. The CLT system offered easy integration with Passivhaus energy efficiency and airtightness requirements.

One of the great things about using a modular offsite CLT system is the efficiency of the build. The main construction of the building only took three weeks, which helped us make sure we met our deadlines and kept the momentum of the build moving swiftly while keeping our embodied carbon as low as possible.

Richard Dudzicki, Director, RDA Architects

Embodied carbon

Material choices and construction methods were guided by the PHRibbon tool's embodied carbon analysis. The use of CLT as the main construction method helped reduce the project's embodied carbon.

U-values

Floor: 0.095 to 0.154 W/m²K

Polished concrete, beam and block

Wall: 0.079 to 0.217 W/m²K

CLT & insulation, full brick

Roof: 0.092 to 0.162 W/m²K

CLT & insulation, ceramic roof tiles

Building performance

Designed energy performance

Airtightness n₅₀ (≤ 0.6ACH @ 50 Pa)

0.5 @ 50 Pa

Space Heating Demand (≤ 15 kWh/m².a)

13 kWh/m².a

Heating Load (≤ 10 W/m²)

8 W/m²

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

25 kWh/m².a

Primary Energy Renewable Generation

13 kWh/m².a

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

Services

An air source heat pump supplies heating to the home while an MVHR ventilation system delivers optimal indoor air quality. The MVHR supply and extract ducts are disguised in the false traditional chimney. The house is equipped with smart technology for controlling heating, hot water, and ventilation.

The roof's raised pitches accommodate solar PV panels. A pergola in the garden offers summer shading to avoid overheating.

Key team

Architect: RDA Architects
Passivhaus Consultant & M&E Consultant: Ecospheric
Contractor: Pawel Polowiec
Structural engineer: Michael Hadi Associates
Passivhaus Certifier: MEAD Consulting

This is the latest in several award-winning Passivhaus homes by PHT member RDA Architects. To discover more self-build Passivhaus projects, visit one this June in the International Passivhaus Open Days..