How much per square foot?” — not a day passes by in our architectural practice where this question is asked multiple times. With up to 60 per cent of the cost of buildings going towards materials, it is no wonder that the choices we make while specifying these will have a large implication on the final costs of the building construction.
A building material is defined as anything that can be used for construction. These can be natural like clay, rock, sand and wood or produced through a manufacturing process like steel and glass. Historically, there has been a trend in these materials going from being natural to becoming more processed and composite; biodegradable to imperishable; indigenous (local) to being transported globally; repairable to disposable. These trends tend to increase the initial and long-term economic, ecological, energy, and social costs of building materials. In today’s world, it is impossible to focus only on the economic cost per square foot, as this criterion alone doesn’t do justice to the overall specification. We have to consider the other costs as well.
The initial economic cost of building materials is the purchase price and is the biggest driver in choosing a particular material for building. Sometimes, people take into consideration the energy savings or durability of the materials and see the value of paying a higher initial cost in return for a lower lifetime cost, but this requires a fair amount of convincing for the average consumer.
Ecological costs consider how polluting the material is at a macro and micro scale. At a macro level, the manufacturing process of the material could have a severe environmental impact like mining, using petroleum, and logging. All of these produce environmental damage at source. Transportation is another macro polluter. While moving raw materials, manufacturing, retailing and installation, there is a lot of transportation that adds to the ecological cost of the material. This qualifies as the carbon footprint of the material, and the total greenhouse gas emissions produced through its life have to be thought through.
On a micro level, the material could be contributing to indoor air pollution. A lifecycle analysis includes the reuse, recycling, or disposal of construction waste. Green Building Ratings and principles of sustainable development are systems that take into account the ecological economics of building material and can be useful tools to keep these impacts under check. Initial energy costs include the amount of energy consumed to produce, deliver and install the material. The long-term energy cost is the economic, ecological, and social costs of continuing to produce and deliver energy to the building for its use, maintenance, and eventual demolition. This embodied energy depends on how the materials and design help minimise the lifetime energy consumption of the structure.
Social cost considers the health of the people producing and transporting the materials and potential health problems of the building occupants if there are problems with the building. Even the opening and closing down of manufacturing facilities in terms of job creation and losses are considered a social cost of the material. ‘How much per square foot?’ does not have such a simple answer anymore, as it depends on how comprehensively we are willing to look at it.