H.R. Schipper

Business case study for the zero energy refurbishment of commercial buildings

To achieve higher sustainability of steel reinforced concrete structures, their service life should be extended. When subject to chloride induced steel corrosion, time dependent repair works are most probably inevitable. Evidently, this results in extra concrete manufacturing and thus more environmental impact. Cracks offering direct pathways for the corrosion inducing substances play a very detrimental role in this. This paper presents the potential of using self-healing concrete to cope with this problem. By incorporating a polyurethane (PU)-based healing agent that is adequately released upon crack occurrence, chloride ingress is hindered substantially and onset of active corrosion is postponed. The required number of repair actions within 100 years could then drop to zero. Nevertheless, the implementation of a self-healing mechanism comes along with a higher initial cost and additional environmental impacts. Therefore, the necessary cost and life cycle assessment calculations have been performed as well. It was found that the cost of the PU-based healing agent is very reasonable while the extra costs of the capsules are for the moment still unacceptable. Environmental burdens associated with the PU precursor filled capsules are negligible (0.1-4.8%) in comparison with the impacts related to regular concrete repair to meet the design service life of 100 years.Concrete is the most manmade material solution produced and used worldwide. Its cornerstone is the cement composite due to the high emissions level and resources consumption volume. Roughly 5-7% of global carbon dioxide emissions come from cement manufacture process. The far-reaching alternative of replacement a clinker portion in the cement material composition has gained consensus. It becomes relevant in emerging economies since in the short-run there is not widely available ways for increasing the production capacity while diminish the environmental impact with no additional investment cost. Low carbon cement (LC3) is leading the contemporary paths towards facing environmental challenges and resource scarcity. This article aims at assessing the theoretical consideration of replacement of the Cuban traditional cements by LC3 according to housing case studies in Villa Clara province. On the basis of LCA background and the supply chain rationale, a procedure for discussing sustainable contribution of LC3 is designed and applied. Hollow blocks and mortars have been included in the calculations as well as the manufacturing/transportation processes for the entire supply chain of one semi-detached two-storey row houses built in the core of a slum-like settlement at Condado suburb-Santa Clara city. This approach demonstrates that the LC3 incorporation in the Cuban construction sector could afford considerable economic savings with the subsequent contribution in favour of the environment.Net zero energy is already an ambitious target for several buildings, especially since the DIRECTIVE 2010/31/EU that requires increasing the number of nearly zero energy buildings. The existing commercial building stock needs to be included in order to achieve the 2020 EU environmental targets. The main barriers of zero energy refurbishment of existing nonresidential buildings appear to be financial rather than technical, next to a number of other extrinsic factors that do not stimulate such an investment. While a business case for new zero energy buildings is believed to exist, controversial opinions can be found with respect to refurbishment of large buildings. The present study aims to identify the factors that affect the feasibility of the zero energy refurbishment of existing commercial buildings, while suggesting ways to create the business case addressing the Dutch market. Through interviews with real estate investors, the study identified the financial and technical barriers encountered today to undertake deep energy retrofit. Subsequently, the design interventions needed to refurbish a Dutch office building and meeting the net zero energy target were evaluated using a software complying with the Dutch standards NEN 7120. A risk and sensitivity analysis with Monte Carlo simulations showed the influence that design aspects, energy price and landlord-tenant agreements have on the business case. The study has concluded that a business case considering the energy savings alone is not sufficient to convince investors. However, when the design provides additional benefits, such as increasing the property value, the refurbishment can become feasible. This is an important observation to promote the refurbishment towards a zero energy building stock.Concrete is, after water, the most used material worldwide and its demand is projected to growth in the next 30 years. Among all concrete materials, cement presents the higher energy consumption and carbon emissions, thats why this industry has been developing several alternatives to gain sustainability. Reduction of clinker ratio by using Supplementary Cementicious Materials (SCM) allows a better use of existing capacities with low investment while a reduction in emissions, costs and energy per ton of cement is observed. The objective of this article is to assess the environmental and economic impact of a new cement with 50% of clinker: Low carbon cement (LC3). A procedure for evaluating sustainable and economic contribution of LC3, while projected demand is satisfied, is designed and applied in several scenarios. The results demonstrate that LC3 introduction is the best option to meet growing demand considering capital investment options in non-developed countries conditions with a reduction of ~30% in carbon emissions, of ~10% in costs and a faster return on investment related to OPC figures in Cuba.