The challenges of eco-retrofitting interiors

Brian Murphy | National Green Specification

The interior design profession is coming around to the idea that refurbishment jobs need to take into account the environmental impact these projects have and to address this, The Green Register is holding a seminal one day conference in London on 9th February to address some of the more pressing issues interior designers have to face. But what are these issues?

Since interior finishes are removed and replaced frequently, the building-fabric-only needs to be competent or every refit would require building regulations applications, associated design and application fees and increasing energy performance requirements would make refit progressively more expensive. Issues that need to be addressed by the building include: G value/solar gains/thermal mass /U value/decrement delay/wind and airtightness/thermal breaks/weather tightness/vapour permeability/internal surface temperatures etc.

No tenant/purchaser would want to buy into inadequate property that needs them to complete it as part of the fit out and tenant agreement. The Tenant would quite rightly expect a competent building. If building running/heating/ventilating/cooling are part of their landlord agreement there is no incentive to reduce costs unless they see a financial return for a consumption reduction. Carpets may be insulating but they will have an effect on the ground floor only and they also hide thermal mass that can have an effect on the overall energy demands. The same two points apply to suspended ceiling, not the ground floor, but the roof.

The interior finishes can have variable properties that help of hinder regulating internal conditions and comfort conditions hence affecting heat/vent/coolth requirements. The same finishes with the wrong choice of materials can affect indoor air quality and the need for ventilation which drive up energy costs. Issues of concern include: material ingredients/binders/adhesives/VOCs/off-gassing/indoor air quality/moisture mass/ thermal mass/acoustic mass etc.

Increasing internal insulation of historic buildings by wall coverings can lead to condensation, mould, asthma, rot, toxic mould, frost damage. In my limited past experience the level of technical expertise in IDs (who often have to rely on manufacturers reps to tell them what they need to choose and specify) is below Architects who themselves can still be inadequate in these matters, so I would be worried about this too. Issues to be address here include vapour permeability/capillary action/continuity/gap avoidance/moisture transport.

The RICS ‘Ska rating’ assessment process addresses refit better than any of the BREEAM tools – it focuses on building fabric and the materials that both IDs and Architects specify. But I think it follows the conventional approach (competent building, complimentary interiors) More importantly it addresses reuse of existing interior materials and reuse of reclaimed rather than sending perfectly sound materials to landfill.

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