Insulation needs to keep performing to be green
But how green can a roofing system be? Ideally it should not only use construction methods and materials and with the highest insulation performance, but these materials should also be green in their own right.
Modern building methods tend to use lightweight materials that can be quickly assembled on site to produce cost-effective buildings that nonetheless have excellent as-built energy efficient performance. Their lightweight construction does however result in a low thermal mass – the building’s ability to retain heat to even out temperature fluctuations. This means that a highly-efficient thermal insulator must be used to counteract this. At the same time, this insulation must itself be made of a lightweight material.
Rigid insulation panels using Polyurethane (PUR) and Polyisocyanurate (PIR) foams have proved to be an excellent answer to these requirements by combining a high strength-to-weight ratio with excellent thermal performance. Above and beyond this though, PUR and PIR are green materials in their own right.
As Paul James, Technical manager of EcoTherm, a world-leading manufacturer of these products, explains, “There are two reasons why these products are green: they are made in a sustainable process with sustainable materials, and their durability means that they keep on performing for the life of the building.”
The manufacture of the PUR and PIR boards uses no CFCs or HCFCs so they have an ozone depletion potential (ODP) of zero. They also have a global warming potential (GWP) factor of three, which compares extremely well with the target level of five.
EcoTherm has now introduced products that combine PIR and PUR with other sustainable materials. Eco-Deck is an insulated decking board designed to be used on flat roofs for both residential and commercial buildings. It has a laminated sandwich construction in which the PUR foam board is faced with aluminium foil on the underside and has a plywood deck on top.
The aluminium foil is inherently recyclable and made from a high proportion of recycled metal, and now the plywood has impeccable green credentials too.
EcoTherm ensures the wood that goes into the plywood comes from sustainable sources in Brazil and Argentina that are fully certified under the Forestry Stewardship Council scheme (FSC certificate CU-COC-806092).
The Forestry Stewardship Council is an independent, international organisation that was established to promote responsible management of the world’s forests by setting standards and running the FSC certification and labelling scheme. It brings together forestry management companies, logistics suppliers and manufacturers of wood-based products to ensure that there is an unbroken ‘Chain of Custody’. This is an audited record of every step in the path taken by the timber from the forest to the customer – including processing, transformation, manufacturing and distribution.
FSC certification ensures that all organisations in the Chain of Custody consistently operate to legal and sustainable standards. As a safeguard, Chain of Custody documentation must be obtained from the supplier at the time of purchase, and all certified timber must be clearly identifiable so that it can be directly linked to the supplier’s documentation. Every invoice and delivery note must clearly show which items are certified and refer to the suppliers of the Chain of Custody certification. This level of traceability is increasingly becoming a requirement for many large commercial and government contracts.
“We previously sold EcoTherm Eco-Deck with standard ply and we know that installers like it for providing both insulation and deck in a single fix. By sourcing FSC supplied timber we can now satisfy the growing demand for sustainable products for eco building too,” says Paul James.
The final argument for PUR and PIR boards as ideal green insulation materials is their durability. EcoTherm says that the life of these products will almost certainly be longer than the buildings they are used in, with no degradation in performance over that time.
Alternative materials such as mineral wool and insulation materials derived from vegetable and animal product (cellulose and sheep’s wool for example) are susceptible to various factors which can reduced their insulation efficiency over the life of the building.
This means that the building either loses unacceptable amounts of energy – so more carbon emissions are generated in making up the deficit – or that valuable natural resources are used to replace the non-performing materials.
“Our BBA certificates cite a performance life of 30 years and we have carried out accelerated ageing testing that predicts a performance life in excess of 50 years. But there is no reason why these materials should not last indefinitely. They have a closed-cell structure that makes them impervious to the effects of damp or condensation, and as rigid boards they are not prone to settling. We wouldn’t expect them to need replacing at any point, and they would only normally be removed when the building is demolished. Even then they are green as they can be fully recycled,” says Paul James.