Beachfront environmental hub

A certified Passivhaus environmental hub has opened on the seafront on one of Bournemouth’s Blue Flag beaches. The Durley Chine Hub, commissioned by BCP Council, aims to achieve a step-change in the reduction of waste and elimination of single-use packaging along Bournemouth, Christchurch and Poole’s seafront. Around 2,000 tons of waste is removed from these beaches annually. The new hub's mission is to educate and change behaviours along the seafront.

The new hub needed to demonstrate strong environmental credentials. PHT member Footprint Architects proposed a design that combined low operational energy, choosing Passivhaus certification for the education and welfare part of the building, with low embodied carbon materials.

The hub building consists of a refreshment kiosk, public WCs, and a two-storey education building with welfare facilities for beachfront staff.

The internal floor area was reduced and rationalised during the design process by separating functions into independent buildings with differing insulation and ventilation needs.

Key stats

Construction: Timber frame
TFA: 196 m²
Build start date: 2021
Completed: 2022
Certified: Passivhaus, 2023

Durley Chine Hub. Image credit: Footprint Architects, Photographer: Richard Chivers

This highly-insulated, Passivhaus certified, timber framed education, welfare and exhibition space commissioned by client BCP, is a beacon for low carbon innovation and what can be achieved when you move beyond the traditional construction pathway. The building is designed to be net zero in operation and has been designed with low embodied energy construction.

Peter Ward, Director, Footprint Architects

Construction

Offsite modular timber frame construction minimised the building's embodied energy and is relatively quick to build, advantageous for the public seafront location. Offsite construction also helped to reduce the disruption to the seafront ecology, reducing construction delivery traffic.

Durley Chine Hub. Image credit: Footprint Architects, Photographer: Richard Chivers

Embodied carbon

Keeping the kiosk, storage areas, WCs, and some of the learning space outside the thermal envelope reduced the use of insulation materials and, therefore embodied carbon. The public toilets are unheated and uninsulated structures, and the kiosk has low levels of insulation and minimal heating demands. Designing out unnecessary spaces or finishes, simplifying as much as possible, incorporating natural materials and reducing the use of plastics was a priority for the project team. .

Examples of features with low embodied carbon include the use of 52 tons of reclaimed groynes in the building canopy, and timber from a decommissioned German submarine base was used for decking. Locally sourced sand and aggregate were used for the kiosk building. Ground granulated blast-furnace slag (GGBS), a byproduct from the iron industry, was specified as a low cement concrete. Concrete structures were designed with almost no need for steel reinforcement, and aggregate recovered from the site demolition was used as piling matt and substrate; Recycled glass was used in the eco screed, and recycled newspapers were used as insulation.

The provisional assessment results of the project's Embodied Carbon Calculation, based on RICS whole life Carbon Assessment Method, were:

Upfront Carbon: 210 kgCO2e/m²
Embodied Carbon: 172 kgCO2e/m²
Sequestered Carbon: - 225 kgCO2e/m²

U-values

Floor: 0.047 W/m²K

Eco screed, EPS insulation, concrete slab

Durley Chine Environmental Hub. Image credit: Footprint Architects

Wall: 0.11 W/m²K

Timber frame, insulated with recycled newspaper.

Roof: 0.097 W/m²K

Timber I-beams, with wood fibre and recycled newspaper insulation.

Building performance

Designed energy performance

Airtightness n₅₀ (≤ 0.6ACH @ 50 Pa)

0.6 @ 50 Pa

Space Heating Demand (≤ 15 kWh/m².a)

15 kWh/m².a

Heating Load (≤ 10 W/m²)

12 W/m²

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

72 kWh/m².a

Overheating %

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

Durley Chine Environmental Hub. Image credit: Footprint Architects, Photographer: Richard Chivers

Durley Chine Environmental Hub. Image credit: BCP Council

Services

The hub is an all-electric building, with the all-electric catering equipment linked to the 90m² array of roof top mounted solar PV panels. MVHR (mechanical ventilation with heat recovery) is used for the education building. The shading strategy, to minimise overheating, is provided by a brise-soleil.