Inger Andresen

Comparative emission analysis of low-energy and zero-emission buildings

ABSTRACT Different designs and concepts of low-energy and zero-emission buildings (ZEBs) are being introduced into the Norwegian market. This study analyses and compares the life cycle emissions of CO2 equivalents (CO2e) from eight different single-family houses in the Oslo climate. Included are four ZEBs: one active house, two passive houses, and a reference house (Norwegian building code of 2010). Monthly differences in CO2e emissions are calculated for the seasonally sensitive Norwegian context for electricity generation and consumption. This is used to supplant the previous applied symmetric weighting approach for CO2e/kWh factors for import and export of electricity for the ZEB cases. All the ZEBs have lower use-stage emissions compared with the other buildings or the reference case. Embodied impacts are found to be 60–75% for the analysed ZEB cases, confirming the importance of embodied impacts in Norwegian ZEBs. The lowest total emissions were from the smallest ZEB, emphasizing area efficiency. The highest emissions were from the reference case. By abandoning the symmetric approach, a new perspective was developed for assessing the performance of ZEBs within the Norwegian context. One of four ZEB cases managed to balance out its annual energy-related emissions.

Moisture conditions in well-insulated wood-frame walls. Simulations, laboratory measurements and field measurements

Abstract Buildings for the future, that is, zero emission buildings and passive houses, will need well-insulated building envelopes, which include increased insulation thicknesses for roof, wall and floor constructions. Increased insulation thicknesses may cause an increase in humidity levels and thereby increased risk of mould growth. There is need for better knowledge about moisture levels in wood constructions of well-insulated buildings, to ensure robust and moisture-safe solutions. Various envelope constructions were simulated using HAM-tools (Heat, Air and Moisture). In addition, a laboratory experiment was performed to investigate the effect of a slower drying out of built-in moisture. Walls with varying insulation thicknesses and with a high degree of built-in moisture were instrumented with moisture sensors, and the drying speed was monitored. A field monitoring of wood moisture levels and temperatures was performed in wall and roof constructions of five passive houses in three different locations representing different climate conditions in Norway. The general conclusion is that the risk for mould growth increases somewhat in well-insulated envelopes compared to more traditional envelopes. However, in most cases this can be counteracted by making the right choices during design and construction.

Design Strategies for Low Embodied Carbon in Building Materials

The zero emission building (ZEB) research centre in Norway has a series of concept and pilot buildings that investigate design strategies for low embodied carbon in building materials in order to achieve a net ZEB balance; these include two conceptual studies or virtual building models (ZEB office building and ZEB single-family house) and six pilot buildings (Powerhouse Kjorbo, Campus Evenstad, Heimdal high school, Multikomfort house, Living Laboratory and Skarpnes). According to the centre’s definition, a net ZEB balance can be achieved by offsetting the life cycle greenhouse gas (GHG) emissions through the production and exportation of on-site renewable energy. This balance becomes ambitious if embodied carbon from building materials is also considered. Experiences collected from the ZEB pilots demonstrate that a combination of carbon reduction design strategies are necessary in order to achieve this net ZEB balance.

The Role of Utility Companies In Municipal Planning of Smart Energy Communities

Bergen and Oslo municipalities focus on integrating energy concerns into city planning and regard this as an opportunity to further lower greenhouse gas emissions. Due to a lack of tools and clear definitions of what Smart Energy Communities (SECs) are and how planning should be done in order to affect the overarching emission reduction goals, utility companies end up taking a leading role as advisors and influence definitions and strategies in the final design. Based on two case studies of SEC projects in Norway, the authors highlight the need for increased work to create feasible and understandable definitions and strategies for the planning of SECs. In our case studies, city planners struggle to include energy aspects in the early planning phase and to align their objectives of citizen well-being and reduced private car dependency with energy concerns. At the same time, utility companies respond to the perceived threat of more self-sufficient communities by depicting a role closer to the end-user and by offering a pragmatic cost/benefit view on the planning of energy supply options.