Hyper-local housing with reduced carbon footprint

Life Reusing Posidonia is a Climate Change Adaptation project which aimed to demonstrate how to develop low cost housing which has a significantly reduced carbon footprint.

It also aimed to reduce energy and water consumption and reduce the production of waste during construction and throughout the life of the building.

The project used a “hyper-local” architecture model which links environmental issues with the regional cultures and traditional local architectural techniques.

With respect to the forested surroundings, the architecture is simple by design, not wanting to detract from the natural elements. The selection of a dark facade further immerses the structure into the landscape. Although meant to blend in, the timber facade detailing provides a playful contrast between the blackened timber and timber window frames and roof structure.

Wherever possible, within the challenges of the building location and budget, the team chose natural materials. Locally sourced timber was used for the structural elements and interior and exterior finishes. Wood fibre and cellulose from recycled newspapers is used for insulation. Wood fibre boards are again used for wind protection beneath the ventilated facade. OSB (orientated strand board) was sealed and used as a vapour barrier to avoid the use of foils or membranes.

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The designed team looked at what is produced in the area surrounding the site, and what they found was an inspiring mix of traditional materials and common materials used in completely new ways.

– Locally sourced, dried Neptune seagrass packed into re-used pallets used for ceiling insulation. The efficiency of the seagrass insulation was tested by a local university and it was proved to provide the same insulation qualities as standard insulation products on the market

– Lime concrete with recycled aggregate was used instead of standard concrete, with a 50% reduction in CO2 emissions

– Timber doors and all timber used for the interiors was sourced through a local charity, making use of building items typically thrown away

– Ceramic clay breeze blocks, locally made with no additives, baked in an oven using biomass. The biomass is typically almond shells, pine needles or pine splinters. This is a traditional Moorish method of baking in a kiln oven

– Handmade enamelled ceramic tiles used in the kitchens and flooring

– Locally sourced materials, produced, tradesman and services were prioritised

Passive energy saving systems such as cooling the homes in summer via cross flow ventilation from sea breezes and heating in winter using biomass fuel. Rainwater harvesting will help reduce overall water consumption and a recycling program will help reduce waste.

The project is going through a testing phase to evaluate the construction techniques, water and energy consumption and the overall construction costs, which are expected to be less than a 5% increase in industry standard construction materials and techniques.

The project was financed by the European LIFE + program for nature conservation projects

The project was a collaboration between the IBAVI, the DG of Natural Environment, Environmental Education and Climate Change and was financed by European Commission LIFE program. The architectural collaborators included Carles Oliver Barceló, Antonio Martín Procopio, Joaquín Moyá Costa, Alfonso Reina Ferragut, Maria Antònia Garcías Roig.

Sustainability specs:
– Locally sourced materials and products were prioritised
– Locally sourced dried Neptune seagrass ceiling insulation
– Reinforced lime concrete cooked using recycled oil, was a natural alternative to traditional concrete
– Timber for all the interiors was recycled and sourced through a local charity, making use of items typically thrown away
– Local tradesman and services were prioritised
– Ceramic clay breeze blocks
– The ceramic tiles used in the kitchens and floors have been enamelled by hand
– Reduced carbon footprint through buying locally sourced products and materials

From the architect:

There is a general consensus on the need to reduce carbon dioxide (CO2) emissions. A key means of reducing equivalent CO2 emissions is by reducing energy consumption. Strategies including the implementation of energy performance certificates (Directive 2002/91/EC) can help work towards this objective.

For the building sector reducing energy consumption means taking a lifecycle approach and addressing consumption at each stage, including the sourcing of materials, construction, use and end-of-life. There has been much awareness developed in recent years on the importance of energy-efficient buildings, including the use of insulation, solar panels and efficient lighting systems.

However, more attention is needed on the emissions generated during the construction phase. The manufacture of concrete is currently responsible for 75% of the emissions from the construction sector. There is a need to consider alternative building systems that can reduce CO2 equivalent emissions. An interesting option is through the use of local resources with low embodied energy and a return to traditional methods of architecture.

Posidonia oceanica (Neptune grass) is a seagrass species endemic to the Mediterranean. On the Balearic island of Formentera, P. oceanica has been traditionally used in multiple applications, including the thermal insulation of buildings.