The affordable housing development consists of terraced townhouses with apartments on separate plots close to the edge of railway line in a town near Barcelona.
The scheme was designed to form a community with shared civic space including communal gardens. The three-story town houses, inspired by London terraces, were clustered in smaller groups and separated by gardens. The layout would also help phased delivery.
In order to keep costs down, the scheme was designed as a modular system with houses of a standard size but with varying projections on the front and rear to differentiate properties.
Terraced houses were three stories high but the modular system meant individual units be bigger or smaller by combining parts of individual units.
A key challenge was the proximity to the site of a high-speed railway line which made it unappealing to most developers and difficult in terms of noise and vibration. The issue was addressed by using elastometric bearings in the foundations with isolating neoprene mats. In addition structural steel connections were developed to allow for small movement.
The cladding system too was selected to avoid cracking and spalling with in-built joints. Glazing panels facing the railway line used Optilam Phon a specialist glazing type to minimise noise transmission.
We also saw the railway line as an opportunity because it meant there was less visible obstruction around the development. Simple acoustic modelling of the rail predicted noise levels at sensitive receptors. Noise barrier design such as sound barriers/ acoustic fences were considered to control rail noise emissions to sensitive receptors. However we finally decided to use landscape features including trees with thick canopies to reduce both sound and visual intrusion.
In terms of sustainability, since the scheme was developed in partnerships with housing trusts, it meant life cycle costs were key drivers. This required a comprehensive approach to sustainability through a framework. Sustainability KPI’s asked us to reduce heating/cooling loads by 50% compared to conventional homes.
This was achieved by a variety of systems. The scheme incorporates large projecting glazed area which act as winter gardens and this feature alone has meant most of houses use very little energy for heating in winter. For summer months, we developed a thermal modelling solution whereby natural ventilation can be induced through the building by stack effect to reduce the need for AC cooling which means summer cooling is only necessary during a short peak period.
The high thermal mass of the building and increased insulation also provides thermal stability. The use of rooftop solar-thermal water heaters also reduces energy demand and the collection of rainwater essential in Spain helps reduce the need for water.
Working with construction specialist, we developed prefabricated modular housing components which reduced design and construction times to weeks. The aim was an adaption of the Open Sustainable Modular Housing System for flexibility, allowing modifications not only in finishes but also in layout. Stakeholders chose from standard units to create the desired development mix and unit size. The system allows units to be adjusted vertically and horizontally to depending on need. The ground level parking space could also be easily used as bedroom for future changes.
The system uses a steel frame structure with panelling constructed in days and preassembled off site. Exterior façades were created using a mix of plaster panels and cement boards. Costs are comparable to traditional construction but time savings are significant, while waste is minimised reducing C02 footprint. The scheme won a regional architecture prize for housing and it seen as an exemplar development for the Barcelona area.