**4. Environmental impacts in the life cycle of buildings**

The construction of a building causes effects on the environment not only in the construction phase but also throughout the building process: the impacts generated by production, from the use phase, up to the impacts determined by the decommissioning of the building and the end of life of materials.

Among the main types of impact we mention air pollution, mainly due to the combustion processes used for the production of energy; chemical and biological pollution of water, mostly caused by urban, industrial, agricultural, and livestock waste; noise pollution, particularly important in urban centers and near airports and communication routes; the effects on the landscape and on the territorial structure due to the construction of large industrial and energy plants, the construction of infrastructures such as ports, airports, railways, and motorways; and the health and environmental effects, due to accidents that can occur in plants with a significant risk, such as nuclear power plants, hydroelectric plants, and chemical plants. These environmental effects have a common feature: they can be quantified. This makes it possible to use scientific methods to be able to assess their extent.

#### *Life Cycle Assessment in Architecture as Decisional Tool in the Design Stage DOI: http://dx.doi.org/10.5772/intechopen.112011*

There are numerous types of impact, the global effects (greenhouse effect and acid rain) and the effects on the balance of ecosystems, which are only partially quantifiable and which therefore must be analyzed with empirical, conservative, semiquantitative or, depending on the case, simply dictated approaches by public acceptability requirements.

The pure scientific method is not sufficient to give a complete answer to the numerous environmental problems generated by the design of manufactured articles; however, attempts are underway to optimize the assessment of environmental impacts, the main objective of which is to investigate the compatibility between a given project and the environment. Some precautions must be taken at several levels in the building sector, to foresee (and not only ascertain) all the possible causes of environmental impact: at the design level by analyzing different alternatives of materials and technical elements, to obtain the suitable solution, with the best performance and minimum consumption; at the manufacturing industry level to control the quality of the production process and reduce waste and emissions into the environment during the processing chain; in the construction phase of a building, with an improvement in times and construction site processes; in the operational and management phase of the product, with an optimization of consumption (thermal, electrical) for air conditioning, lighting, and household appliances.

#### **4.1 Impacts in the production phase**

Building materials and components are the result of the transformation of raw materials, using energy. From the raw material to the semifinished products, to the finished product, to reach the waste product at the end of its function, each intermediate phase necessary for the processing of the material requires energy which accumulates in the product (as a quantity of incorporated energy) or is released in the environment in the form of heat. In going through the various subphases of the production processes of a building material, one learns how all the levels contribute to the impacts on the environment. In the procurement of raw materials, enormous quantities of materials from quarries and mines are eroded, disfiguring the landscape, as well as consuming nonrenewable materials. Furthermore, it is unthinkable to foresee the future use of only renewable sources, since these too, in addition to not being inexhaustible, have effects on the territory: to build in wood, extensive cultivation of trees is needed to procure raw materials. Once again, the importance of placing the choices in the context of the project and evaluating the exploitation of raw materials, whether exhaustible or inexhaustible, is evident.

The *impacts relating to transport* should not be underestimated. Unfortunately, today, with the globalization of markets and the evolution of construction technology, it is no longer possible to think about the local procurement of materials. Above all, given the heterogeneity of the products on the market, it is no longer easy to check the origin of the same, so the movements that a product carries out in the early stages of its life, up to its transfer to the construction site for which it is intended, cause significant impacts on the environment.

The *actual manufacturing phase* generates, due to the consumption of energy and emissions of waste materials and harmful substances, the greatest pollution in the supply chain, as well as in the entire life cycle of a building. The willingness of companies to reduce the resources and energy used (mostly lost during processes in the form of heat) is slowly entering, thanks also to actions coordinated by trade associations, as well as by national regulations; however, a certain difficulty remains in the management of waste from manufacturing scraps or industrial processes.

#### **4.2 Impacts during the operational phase**

There is a clear urgency to intervene on management consumption (heating, air conditioning, lighting, ventilation, consumption of household appliances, etc.) with greater attention to the efficiency of production processes and impacts on the environment.

Carbon dioxide emissions, responsible for climate change, are proportional to primary energy consumption, with different weights depending on the primary energy carrier (methane, LPG, petrol, diesel, fuel oil, and coal). It is necessary to analyze the consumption of primary energy, for the assessment of the environmental impacts of the national energy system. The forms of pollution linked to local energy consumption, due to the emission of toxic substances such as unburnt products such as carbon monoxide (CO), such as nitrogen oxides (NOx), and such as dust and specifically the articulated (PM10) are dangerous to human health, locally and in the short term, have practically no effect on the global climate.

However, pollutants are generated in concentrated points, such as industrial centers and urban areas. Around every large city, there is a cloud containing polluted gases and dust, noise and light disturbances, with local phenomena affecting health. The widespread distribution of pollution sources makes a systemic approach to their management difficult. We have to think that from these poles, pollution spreads over the entire planet.

Works that could contribute considerably are the rehabilitation of the existing envelopes, a more adequate design of the envelopes in new buildings; a regulation of the summer conditioning; the introduction of automated management systems and the use, where possible, of renewable energies. The restoration of the envelopes allows the reduction of consumption for heating and is a binding condition for the installation of summer air conditioning.

#### **4.3 The post-consumption phase**

At the end of the life span of single systems/components or of the whole building, we are faced with enormous volumes of waste, if we consider the high quantity of building materials used every year.

Due to the variety of substances contained in construction products, disposal operations are not always easy to plan: there are more and more substances that are highly harmful to the environment and human health, so disposal in landfills is not enough, but it is necessary to resort to the collection of special waste. And furthermore, while planning the demolition and disposal, right from the design stage, the time between the production stage and decommissioning is too long. Therefore, it is desirable to opt for preventive actions, i.e. designing buildings with reversible construction methods, which facilitate the disassembly and selective demolition of the parts, allowing, where possible, material recycling operations. It is necessary to introduce Design for Disassembling (DfD) among the design paradigms, trying to predict, in the design of a product, the scenario at the end of its useful life: this principle also affects the choice of construction technologies and materials and components, whose durability must be known. Being able to predict the treatment of a material or component at the end of its service life can imply the improvement of the manufacturing process and the orientation of construction choices toward precise technologies.

A material can be made with reduced impacts in the production chain, but, if landfill is destined, the initial advantage, in a life cycle balance, is compromised.

Predicting today an end of life in place only in a few years takes on a forecasting nature: now we know the means and processes of treatment in current practice, but the future scenario, through technological innovation and more in-depth knowledge of the temporality of new materials, can be completely different.
