André Coelho

Influence of construction and demolition waste management on the environmental impact of buildings

The purpose of this study is to quantify comparable environmental impacts within a Life Cycle Analysis (LCA) perspective, for buildings in which the first (Materials) and last (End of Life) life cycle stages are adjusted to several waste/material management options. Unlike most LCAs, the approach is top-down rather than bottom-up, which usually involves large amounts of data and the use of specific software applications. This approach is considered appropriate for a limited but expedient LCA designed to compare the environmental impacts of different life cycle options. Present results, based on real buildings measurements and demolition contractor activities, show that shallow, superficial, selective demolition may not result in reduced environmental impacts. Calculations actually show an increase (generally less than 5%) in most impact categories for the Materials and End of Life stages because of extra transportation needs. However, core material separation in demolition operations and its recycling and/or reuse does bring environmental benefits. A reduction of around 77% has been estimated in the climate change impact category, 57% in acidification potential and 81% in the summer smog impact (for the life cycle stages referred).

Environmental analysis of a construction and demolition waste recycling plant in Portugal Part I: Energy consumption and CO2 emissions

This work is a part of a wider study involving the economic and environmental implications of managing construction and demolition waste (CDW), focused on the operation of a large scale CDW recycling plant. This plant, to be operated in the Lisbon Metropolitan Area (including the Setúbal peninsula), is analysed for a 60 year period, using primary energy consumption and CO2eq emission impact factors as environmental impact performance indicators. Simplified estimation methods are used to calculate industrial equipment incorporated, and the operation and transport related impacts. Material recycling--sorted materials sent to other industries, to act as input--is taken into account by discounting the impacts related to industrial processes no longer needed. This first part focuses on calculating the selected impact factors for a base case scenario (with a 350 tonnes/h installed capacity), while a sensitivity analysis is provided in part two. Overall, a 60 year global primary energy consumption of 71.4 thousand toe (tonne of oil equivalent) and a total CO2eq emission of 135.4 thousand tonnes are expected. Under this operating regime, around 563 thousand toe and 1465 thousand tonnes CO2eq could be prevented by replacing raw materials in several construction materials industries (e.g.: ferrous and non-ferrous metals, plastics, paper and cardboard).

Generation of construction and demolition waste in Portugal.

In line with the growing concern around the world about construction and demolition waste (CDW) management, an attempt has been made to quantify the amount of CDW generated in Portugal, a country where no reliable/official data exist. This is an increasingly important concern of companies, businesses and municipalities involved with CDW, in a context of rising demands and more demanding recent legislation. One methodology is presented to quantify the present generation, and another to extrapolate this generation over the next few years, up to 2020. It is concluded that at present substantially less CDW is generated than the figure usually cited for Portugal, based on Spanish estimates, although it is predicted that this value will be higher on a 10-15 year timescale, reaching over 400 kg person-1 year-1.

Environmental analysis of a construction and demolition waste recycling plant in Portugal--Part II: Environmental sensitivity analysis.

Part I of this study deals with the primary energy consumption and CO(2)eq emissions of a 350 tonnes/h construction and demolition waste (CDW) recycling facility, taking into account incorporated, operation and transportation impacts. It concludes that the generated impacts are mostly concentrated in operation and transportation, and that the impacts prevented through material recycling can be up to one order of magnitude greater than those generated. However, the conditions considered for the plants operation and related transportation system may, and very likely will, vary in the near future, which will affect its environmental performance. This performance is particularly affected by the plants installed capacity, transportation fuel and input CDW mass. In spite of the variations in overall primary energy and CO(2)eq balances, the prevented impacts are always higher than the generated impacts, at least by a factor of three and maybe even as high as 16 times in particular conditions. The analysis indicates environmental performance for variations in single parameters, except for the plants capacity, which was considered to vary simultaneously with all the others. Extreme best and worst scenarios were also generated to fit the results into extreme limits.

Distribution of materials in construction and demolition waste in Portugal.

It may not be enough simply to know the global volume of construction and demolition waste (CDW) generated in a certain region or country if one wants to estimate, for instance, the revenue accruing from separating several types of materials from the input entering a given CDW recycling plant. A more detailed determination of the distribution of the materials within the generated CDW is needed and the present paper addresses this issue, distinguishing different buildings and types of operation (new construction, retrofitting and demolition). This has been achieved by measuring the materials from buildings of different ages within the Portuguese building stock, and by using direct data from demolition/retrofitting sites and new construction average values reported in the literature. An attempt to establish a benchmark with other countries is also presented. This knowledge may also benefit industry management, especially that related to CDW recycling, helping to optimize procedures, equipment size and operation and even industrial plant spatial distribution. In an extremely competitive market, where as in Portugal low-tech and high environmental impact procedures remain the norm in the construction industry (in particular, the construction waste industry), the introduction of a successful recycling industry is only possible with highly optimized processes and based on a knowledge-based approach to problems.

Conventional demolition versus deconstruction techniques in managing construction and demolition waste (CDW)

Technological aspects of conventional demolition/deconstruction are discussed, and an economic analysis is performed on a case study, directly comparing these two options. This comparison illustrates that although deconstruction is not yet competitive with conventional demolition, within the conditions established in the study, some deconstruction scenarios do present economic advantages. In environmental terms, from a simplified life-cycle analysis (LCA) approach, it can be concluded that, with current techniques and transportation methods, only significant separation efforts that actually result in re-use of recycling of bulk aggregate materials may lead to sizable environmental impact reductions, compared to a conventional demolition scenario.

Preparation of concrete aggregates from construction and demolition waste (CDW)

This chapter describes and provides data on relevant technological economic and environmental aspects of operating construction and demolition waste (CDW) recycling facilities which, among other output materials (e.g. wood, plastics, metals), produce average to high-quality recycled concrete aggregates. It defines and frames what it might take to achieve, at an industrial level that same quality. Market and economic conditions are discussed, focusing on the CDW recycling facility perspective, as well as environmental consequences of its operation, in a life-cycle assessment (LCA) approach.

Antimicrobial efficacy of alcohol-based hand gels with a 30-s application

Aims:u2002 The objective of this study was to assess the antimicrobial efficacy of alcohol‐based hand gels according to European Norm 1500 (EN 1500).

Experimental validation of PV power output prediction models

Despite the existence of a wide range of photovoltaic (PV) performance models, these can be improved in order to increase their accuracy and applicability, making investment decisions and system sizing an easier task. This work presents the one diode and five parameters model, properly framed with the basic physical concepts, and develops a method of parameters determination based only on PV cell datasheet information. The results are compared with those given by the well known one diode and three parameters model and a validation using experimental data is done. In a first approach an I-V curve validation is analyzed and in a second phase it is studied the model performance in terms of delivered power as compared with the results obtained in a test experimental facility. In general, the results for both validations are good, but a slightly prevalence of the five parameters model is observed. This allows one to conclude that, in most cases, reality is modeled with a satisfactory accuracy for the most common applications.