New insights about the relation between the cost of building materials and their embodied energy

Since the Yom Kippur War, and the subsequent Oil Crisis, the energy issue invaded the political, economic and academic debate. Several manufacturing sectors, the building industry as well, have since been committed to achieving a higher level of efficiency in energy use. Under this framework, starting from the end of the seventies, a specific research branch has been devoted to deepening the issue of the energy embodied in various commodities and goods, and, among others, in the construction materials. Nonetheless, during the following decades, this promising research branch has been partly neglected, due to a prominent interest in the building energy consumption in operation. On the contrary, during the last few years, the embodied energy topic has gone back to be a major research item, according to the growing awareness that the energy used to produce the buildings represents a remarkable share of the life-cycle energy. Such a circumstance is not at all peculiar if we consider high-performance buildings, as is the case of the passive house, and it has been validated by several recent studies. In a currently publishing study, we show that the energy embodied in building products, except for raw materials, is a positive logarithmic function of their production cost. The embodied energy is inferred by the inventory edited by Hammond and Jones at the University of Bath. Besides, the costs are gathered from a price list of building products, which is commonly used to arrange the bill of quantities of any construction project. In this paper, starting from the aforementioned empirical finding, we aim at providing further insights into the relation tying together the embodied energy and the cost of building materials. Rather than assuming one-shot estimates of the costs, for each of the considered building materials, we investigate their variation range. Subsequently, relying on a random distribution of all the costs within the identified ranges, we perform a Monte Carlo simulation. By running several trials of one hundred thousand iterations each, we are able to outline the probability distributions of the interpolation functions. The main empirical findings are as follows: there is a well-established relation between the construction cost and the embodied energy, so the former represents a reliable predictor of the latter, and this relation is stronger for some homogeneous subsets of building products.