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Social housing without any heating bills!

Key dates :Conception : 2009. Sales completion : April 2010. Work : April 2010 to May 2011.

A unique developer joined forces with a community housing office to create a group of four council dwellings in the rural village of Sant-Léry. The building, insulated with recycled newspapers and wood wool does not use any heating for the benefit of its residents.

Introduction

Saint Brieuc

Quimper

Vannes

RennesSt Léry

Saint-Léry

Façade Sud - Photo © Fabienne Briero - Habiozone

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‘To develop eco-friendly housing for all’ is the motto of Habiozone , the project developer. When they first contacted the community housing office in 2007 to build passive council houses, the project seemed foolish. However, people on low income are the ones who would benefit most from low energy bills.To see this project through, it was necessary to meet the restricted council budget and to work in harmony with all parties involved, from the design phase onward. The contractual commitment to low-consumption building and passivhaus certifications

Contexthas driven the involvement of all parties. In accordance with passive construction standards, the chosen architect designed a compact building of 282 sq m – 70.5 sq m per accommodation (with excellent thermal insulation). The heavily glazed areas are south-facing, to take advantage of solar heat. The insulation is made from eco-friendly building materials and the building meets accessibility standards. The 1100 sq m site is sheltered from the wind and shade.

Plan © Le Garzic Achitecte

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The building was built using light, dry materials. The floor is entirely made of wood, on top of a crawlspace. It has been insulated with a 40 cm of German-made cellulose fibre insulation. The finish is made of marmoleum sitting on 20 mm thick gypsum board (Fermacell).The wall structure is made of frames (Class 2 treated spruce) with 45 x 225 cm posts. It is braced with 16 mm plywood boards. 22.5 cm of fibre was blown into the cavity, then covered with a 60mm wood fibre rain-barrier (Pavatherm) and Douglas fir cladding including an air gap.

Building overviewThe roof is made of a steel deck on which 40 mm of polyurethane and 36 cm cellulose fibre are fixed with a vapour barrier.The internal walls are covered with plasterboard or gypsum (Fermacell).The wooden front doors and the wood and aluminium triple-glazed windows come from Alsace (Bieber). The bay windows are not sliding but inward opening. Sun shields support solar panels which power a hot water storage tank, with electric back up.The heat exchanger unit made in Germany (Paul) enables optimal heat recovery.Finally, two 5 m³ rain water tanks are used for the garden and toilets.

Panneaux solaires thermiques- Photo © Fabienne Briero - Habiozone

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Technical focus : Wooden floorIn order to test the construction of four dwellings using light/dry material, the floor is made only of wood, without a concrete slab or concrete blocks. 70 linear metres of glued laminated timber, locally manufactured by a specialist, have been laid on 15 foundation pads. The top of the pads had to be level to reduce future wedging with hardwood. As the beams supporting the floorboards were in contact with the ventilated crawlspace underneath,

they have been thoroughly treated. They measure 500 x 200 mm.Above the suspended beam, I-shaped joists (320 mm) have been fixed, braced by OSB boards. This second layer houses the cellulose fibre insulation.

Coupe © Le Garzic Achitecte

Barriers and solutionsThe head of the real estate firm wanted to anticipate the difficulties as much as possible by fostering collaboration between the various partners from the

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is unnecessary in a passive house, the surveyor agreed to restrict the electrical equipment to cabling and connection to the switchboard and no electric storage heating was installed. On site, the cooperation between trades was facilitated by creating a cooperative (Eco-artisans de l’Yvel). This created a spirit of working together and feeling responsible for each other.As for the residents, they have praised their houses once they moved in. The lack of need for heating was not a fantasy except for the occasional top up during a cold spell. Nevertheless, users of a passive building must be prepared, more than others, to look

Extérieur - Photo © Servane Guihaire - Constructys Bretagne

start. The economic constraints were overcome by adapting the budget from the council. The pantry, carport and solar protection on windows had to be removed as a consequence.It was necessary to convince the insurance company to cover for building defects. As the housing council was already a client and owned a building maintenance service, the cover was easier to get. The surveyor also agreed to be involved in meetings. He was able to help companies come up with technical expertise, especially for the building crawlspace. Regulation makes electric storage heating compulsory. As it

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after the building. For this reason, a guide book was given to the tenants. For example, appliances need to be of good quality. If the fridge is not sealed properly in a passive room which barely cools down, it will over-consume energy. A cooler room, separated from the passive part of the house, would then be beneficial. Also, it is necessary to ventilate the room when a large number of people are in as body heat will act as heating! Finally, sunshades contribute to reducing overheating.

Focus : Where are we going from there ?

The whole experience of building the council houses at Saint-Léry did

Intérieur - Photo © Fabienne Briero - Habiozone

not meet many obstacles. Media coverage promoted the outcome. Tenants are happy. But despite all this, these experiments have not developed. Why is that?Even if the developer believes that eco construction has grown in the last few years, he notices that construction methods have not been fundamentally challenged. Many towns and councils want to put a building or an eco-neighbourhood in the spotlight, but few aim for normalization of passive or eco-friendly housing. Furthermore, councils are reluctant to identically reproduce a successful building even if it is customisable.Finally, public project management puts most of the emphasis on time,

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speed, volume and cost, even if running costs are going to prove more expensive than in passive buildings.

Focus : Purchase on future completionThe real estate programme of the Courtieux area has been sold on future completion to the community housing office. In this type of sales contract, the purchaser (the housing office in this case) becomes the owner of the building only after its completion. The developer therefore keeps full control as main contractor

until the end of the build. This has enabled Habiozone to be relatively in control of technical decisions and able to select the trades. In this type of sale on completion, the developer is required to provide a financial guarantee of completion, which protects the purchaser.

The Domaine des Courtieux obtained the French certificate of (BBC) (low consumption building and the label Passivhaus). It was the first communal dwelling to be certified passive in Western France. It also received an award at the Pyramides d’argent 2012. A thermography study has been

Performance

Maison passive - Photo © Servane Guihaire - Constructys Bretagne

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StakeholdersDeveloper : Habiozone éco-promoteur (Mauron)Public housing office : Bretagne Sud Habitat (Vannes)Project manager : Le Garzic Architecte (Rennes)Contractors cooperative : Les éco-artisans de l’Yvel (Mauron)Groundworks : Bergamasco (Ploërmel)Timber construction : Eurl Briero (Mauron)Internal walls : Rialet (Mauron)Plumbing, electricity, ventilation : Thamin (Mauron)Decorating, Flooring : Sarl Derval (Taupont)Bathroom/sinks : Cochet (Mauron)

Linkwww.habiozone.fr/Logements-Passivhaus.html

Costs Groundwork : £13,935 before taxTimber structure : £67,480 before taxFrame : £11,571 before taxInsulation : £29,099 before taxRoofing : £10,772 before taxJoinery : £59,298 before taxRendering-Plastering : £21,586 before taxElectricity : £11,108 before taxPlumbing : £31,966 before taxFlooring : £11,589 before taxVentilation : £14,813 before taxDecorating : £13,268 before taxCladding : £22,783 before taxDecking : £8,307 before taxTotal construction cost : £327,575 before taxequivalent to £1,149 /sq m before taxMetrology : £15,215 before tax (including subvention of £11,587 )Double certification : £2,500 before taxAirtightness test : £743 before tax

conducted on the building by the CETE (Building technics study centre), which did not detect any thermal bridging. The ADEME (Agency for the Environment and Energy) has financially supported the fitting of sensors in the building to analyse and evaluate its performance in real time. While waiting for the results, the first reports already show that appliances are the greatest consumer of electricity. Except during cold spells, the building does not require heating.

Façade Nord - Photo © Servane Guihaire - Constructys Bretagne

ContactConstructys Bretagnewww.constructys-bretagne.fr