It is time to talk about offsite and Modern Methods of Construction (MMC). Both terms have become widely used in the last few years, promoted by the government as modular construction, a way of delivering housing projects more efficiently, in a safe controlled environment. On the face of it, these methods appear to delivery exactly what we need, but is this the case in reality? And is it the direction we should be heading?
When the government references modular construction it is generally referring to 3D volumetric systems, whereby a building is manufactured offsite in a factory and assembled onsite, and not MMC, although they can be the same thing. MMC encompasses many forms of construction, and in fact using the name is misleading as some types have been around for a very long time and are not new to the construction industry. According to cross-industry working groups, the definition of MMC covers everything from 2D & 3D structural systems to traditional building applied more efficiently. These include timber frame, structural insulated panels, or any type of components to support other methods. 3D construction or volumetric systems are more problematic and limited by transport which dictates module size, add to the ambition of a complete factory finish and connection on site, and you begin to run into other challenges with airtightness, ventilation, thermal bridging and heat loss. The reasons for the government supporting MMC as opposed to ‘traditional’ construction are speed of delivery, and production in a safe environment which is efficient and quality controlled. Such methods can be an excellent approach of achieving better buildings, yet inherently this is the wrong way to view construction, and there are much better things we could, and should, be doing.
Firstly, speed of construction is not our real problem. Build capacity is an economic issue determined by the market, linked to demand, affordability, and the developers’ commercial incentives to manage sales, rather than a technological or construction concern. Regardless of the construction method, and the length of time it takes to build, we should be concentrating on delivering passive house dwellings which require very little space heating demand, and perhaps more importantly the use of natural materials. The more natural the product and less manufacturing processes required also means a return to traditional crafts and the greater benefit to the environment. The time saved using any highly processed method is irrelevant if energy use and the amount of carbon pollution to the environment has not been reduced after construction. To solve the problem, we must first look at what we use to build our dwellings, and then how we construct them. We already possess the knowledge needed to make our homes super efficient, cheaper to run and heathier to live in.
Research carried out by AECB found a house built with single leaf rendered block walls and EPS insulation, emitted 1.6 tonnes less CO2 than the same house built with a brick-clad cavity wall, and 6.8 tonnes less than an Insulated Concrete Formwork wall.
Many Passivhaus projects have been in use for a number of years which demonstrate low energy demand principles, the next step of to make our built environment much more ecological. More innovative bio-based building components are already appearing in the marketplace, yet cheaper unsustainable alternatives are still often specified. Currently there is no option but to build more, so innovation is required using less manufacturing processes to produce building products, and use of materials like steel, concrete, aluminium, and plastic used only as a necessity.
No matter how green and sustainable our building products appear, growth will eventually overwhelm any living ecosystem, so we must prioritise our need within the world in which we live.