Resource efficiency of calcium silicate units

Due to the current importance of sustainability, the federal association of the calcium silicate masonry unit industry has taken intensive interest in the question of the resource efficiency of calcium silicate masonry units and construction and has carried out an extensive investigation to this end. The study subjected all stages of calcium silicate, from raw materials reserves and their extraction, production and use in building to recycling, including all transport routes and energy demands, to detailed analysis and critically examined the sustainability of calcium silicate blocks. The present article explains and evaluates the entire life cycle of calcium silicate masonry units.     

Gebäude aus Lebenszyklusperspektive – Ökobilanzen im Bauwesen

Life cycle assessment in the construction sector. Under the impression of an increasing demand for sustainability thinking in the building and construction sector, the method of Life Cycle Assessment (LCA) is constantly gaining relevance. LCA is a method to quantify and assess the environmental impacts of technical systems – in the building and construction sector, these could be both, building products or complete buildings – over their entire life cycle. In the construction sector, LCAs of building products have been well established, while LCAs of entire buildings are just now becoming more common. The German certificate for sustainable buildings strongly promotes this development by including Life Cycle Thinking into the rating of the sustainability of buildings. Due to this development, planners and other stakeholders in the construction industry have to face the necessity of life cycle based environmental optimization of a building already during the planning phase of the building. With the cooperation of LCA experts and experts in the field of assistance in the planning and construction process, dedicated and feasible solutions for this task can be developed. This article provides an overview on LCA in the building and construction sector and presents a possible approach to the question of planning‐integrated environmental optimization of buildings.     

Environmental impact of construction products – possibilities and limits when comparing different wall constructions

Life cycle assessments quantify the environmental impact of goods and services. Increasingly, their results should be used for variant comparisons in construction planning and procurement. For the ecological assessment of wall building materials, this should not be limited to the assessment of the blocks, but the influence of insulation, plaster and mortar have to be taken into account as well. The considered wall should also fulfil predetermined properties such as a certain U‐value. The LCA data available today still do not permit any comparison of variants. For this, product‐specific life cycle assessments/environmental product declarations would have to exist on the basis of uniform background data. Because the latter are being constantly developed and there are hardly any product‐specific calculations, comparisons today are very inaccurate and subject to great uncertainties.     

Autoclaved aerated concrete with sulphate content: an environmentally friendly,durable and recyclable building material

Autoclaved aerated concrete (AAC) contains a small quantity of sulphate. For example, a modern quality class PP2‐0,35 AAC (λ = 0.09 W/(mK)) from Xella contains about five per cent by mass of sulphate in the form of gypsum or anhydrite. The addition of sulphate reduces shrinkage and enhances compressive strength and durability. AAC thus has an almost unrestricted lifetime. Regarding the environmental acceptability of sulphate, dogmatic discussions have been held for years. What is certain: sulphate is not a hazardous substance. Calcium sulphate (gypsum) has been categorised according to the Directive (EC) No. 1272/2008 (CLP) as not hazardous. Xella's voluntary environmental declarations for AAC confirm not only the excellent ecological balance of this product but also the absence of hazardous substances. For construction and demolition (C&D) waste from AAC, disposal is ensured in Germany with landfill class I (“Non‐hazardous waste, domestic waste”). In order to save disposal costs, Xella offers to take back unmixed cutting waste, which arises in the course of new building or refurbishment, without charge at the Ytong‐factories. Xellas long‐term aim is a closed recycling loop for AAC. A collaborative pilot project between Xella and the Otto Dörner Entsorgung GmbH has shown that from the point of view of process and materials technology, production of high‐quality AAC is even possible under utilization of crushed AAC from demolition.