Abstract

The application perspective of aerogel glazings in energy efficient buildings has been discussed by evaluating their energy efficiency, process economics, and environmental impact. For such a purpose, prototype aerogel glazing units have been assembled by incorporating aerogel granules into the air cavity of corresponding double glazing units, which enables an experimental investigation on their physical properties and a subsequent numerical simulation on their energy performance. The results show that, compared to the double glazing counterparts, aerogel glazings can contribute to about 21% reduction in energy consumptions related to heating, cooling, and lighting; payback time calculations indicate that the return on investment of aerogel glazing is about 4.4 years in a cold climate (Oslo, Norway); moreover, the physical properties and energy performance of aerogel glazings can be controlled by modifying the employed aerogel granules, thus highlighting their potential over other glazing technologies for window retrofitting towards energy efficient buildings. The results also show that aerogel glazings may have a large environmental impact related to the use of silica aerogels with high embodied energies and potential health, safety and environment hazards, indicating the importance of developing guidelines to regulate the use of aerogel glazings.

The paper aims to investigate whether it is possible to achieve a net Zero Emission Building (nZEB) by balancing emissions from the energy used for operation and embodied emissions from materials with those from on-site renewables in the cold climate of Norway. The residential nZEB concept is a so-called all-electric solution where essentially a well-insulated envelope is heated using a heat pump and where photovoltaic panels (PV) production is used to achieve the CO_2eq balance. In addition, the main drivers for the emissions are revealed through the CO_2eq calculation for a typical Norwegian, single-family house. This concept building provides a benchmark rather than an absolute optimum or an architectural expression of future nZEBs. The main result of this work shows that the criteria for zero emissions in operation (ZEB-O) is easily met, however, it was found that the only use of roof mounted PV production is critical to counterbalance emissions from both operation and materials (ZEB-OM). The results show that the single-family house has a net export to the electric grid with a need for import only during the coldest months. In the next stage of the work, the concept will be further optimised and the evaluation method improved.

In order to reach the goal of a zero emission building (ZEB), CO2 emission data has to be made available and verified for traditional building materials, new ‘state-of-the-art’ building materials and the active elements used to produce renewable energy. However, an initial literature review found that although there are databases of embodied carbon values for most building materials, the range in results for some materials are varied and inconsistent.

This paper follows on from previous work on the development of a transparent and robust method to calculate CO2eq emissions of the materials used in the concept analysis of the ZEB residential model, single family house. The aim of the concept analysis was to investigate if it was possible to achieve an "all-electric" ZEB-building by balancing operational and embodied emissions by PV-production on the building. The analysis has not considered minimising the embodied emissions but is rather a documentation of the embodied carbon dioxide emissions using traditional materials in the envelope and in the ventilation and heating systems, as well as, those associated with the renewable energy system, such as the photovoltaic panels and solar thermal collectors. Material inventories have been imported from the Revit BIM model, via MS Excel. The material inputs are structured according to the Norwegian table of building
elements, NS 3451-2009 and emission factors (kgCO2eq per functional unit) for the calculations are sourced from SIMAPRO/ Ecoinvent version 2.2.

The goal of these calculations is to estimate, and thus provide an overview of the materials and components in the ZEB residential model, which contribute the most to the embodied carbon dioxide emissions. The calculations are based on the principles of environmental assessment through life cycle analysis. It should be noted that in this first round of calculations, not all life cycle phases are included. In the next stage of the calculations, the model will be optimised and the impact on emissions recalculated accordingly

The Research Centre on Zero Emission Buildings - Annual Report 2012

The main aim of the work has been to do modeling and calculations of the energy use, embodied emission and the total CO2-emission for a typical Norwegian residential building. By doing this we try to reveal and study the main drivers for the CO2-emission, and also which performance is necessary for components and solutions in a Zero Emission Building according to the current Norwegian ZEBdefinition.