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This work presents the results of a survey and measurement campaign carried on in two wooden buildings in Trondeim, Norway. These are one tower in a student accommodation complex, the Moholt Allmenning, constituted by five CLT towers of 9 floors each, and a mixed CLT-and-timber-frame educational building, the Haukåsen kindergarten. Both buildings comply with the Norwegian Passive house standard and the kindergarten complies with the BREAAM certification as well. Questionnaires focussing on the buildings' users thermal, acoustic, and visual comfort, and on the IAQ were submitted. Measurements of the indoor operative temperature and CO2 levels were performed. The measurements showed that both buildings are in the NS 15251 Class I with regards to the thermal environment, in both summer and winter. The questionnaires that the perceived dissatisfaction is somewhat higher than that assessed in the measurements, leading to a lower rating, especially in the student housing. One of the most reported issue in the student housing was the noise level, which resulted in 28% of student dissatisfied.

The objective of this paper is to report and analyse strategies for cost reduction, design processes, and procurement models of one wooden nearly Zero Energy Building (nZEB) in Norway. The building investigated in this paper is the Moholt Allmenning, a newly-built student accommodation located in Moholt, Trondheim. Interviews with the building's owner and the contractor were carried out to obtain information on the decision-making process during the procurement phase, the planning phase, and the execution phase. The results show that the environmental goal and the criteria set for the use of wood in the tender announcement were a critical driving force for choosing cross laminated timber (CLT) in the final design. The results also show that the cost of using CLT in student residences is competitive against using concrete and steel. Given the requirement of little greenhouse gas (GHG) emissions from materials production in nZEBs, the use of CLT is however a better choice. The objective of this paper is to report and analyse strategies for cost reduction, design processes, and procurement models of one wooden nearly Zero Energy Building (nZEB) in Norway. This publication is part of the dissemination activities of the EU Horizon 2020 project NERO, whose scope is to demonstrate the feasibility of cost reduction of nZEBs built with wood in the Nordic Countries. Case buildings from Estonia, Finland, Norway, and Sweden are studied with respect to their technological solutions, energy use, and construction cost. The Norwegian building investigated in this paper is the Moholt Allmenning, a newly-built student accommodation located in Moholt, Trondheim. Interviews with the building's owner and the contractor were carried out to obtain information on the decision-making process during the procurement phase, the planning phase, and the execution phase. The results show that the environmental goal and the criteria set for the use of wood in the tender announcement were a critical driving force for choosing cross laminated timber (CLT) in the final design. The results also show that the cost of using CLT in student residences is competitive against using concrete and steel. Given the requirement of little greenhouse gas (GHG) emissions from materials production in nZEBs, the use of CLT is however a better choice.

To achieve a sustainable building stock, it is necessary to focus on existing as well as new buildings. New houses built according to the Norwegian building code are close to nZEB (near Zero-Energy Building) level, but existing buildings contribute a significant share of the energy consumption, and the difference between new and older houses is increasing. As the renovation rate is low, it is important to include ambitious energy upgrading once a renovation project is undertaken. So far, however, there is almost no market for nZEB renovation of small wooden buildings. These buildings are challenging to renovate, and even more challenging to do so with ambitious climate targets. In effect, only half of the renovations in Norway include energy renovation. The demand for ambitious renovation depends on a value proposition that is understood by the customer. Novel and well-designed business models can be central tools for achieving this. In this paper, existing and potential business models for renovation of wooden housing are identified and analysed. This paper is based on the “Energy upgrading of wooden dwellings to nearly zero energy level” (OPPTRE) project. One of the activities for researchers, industry and public partners in OPPTRE is to identify, analyse and assess current business models, and develop novel approaches through collaborative workshops and interviews. The results are documented and elaborated upon by the research team before the next step, which is to test the most promising models. Previous research indicates that only a small share of Norwegian enterprises have changed their business model over time. Two of the reasons for this are lack of critical reflection on existing business models and fear of changing the status quo. A third reason is lack of knowledge of how to manage the transformation process. In the process of identifying existing and developing novel business models, the partners in OPPTRE explore new opportunities to promote ambitious energy upgrading. Their commercial performance is likely to increase through the focus on business model design. New business models may also help increase the uptake of innovative energy solutions in the renovation market for small wooden buildings.

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 building sector is responsible for several environmental impacts, as well as economic and social consequences. Hence, the adoption of energy efficiency measures in building renovation projects can lead to benefits to several stakeholders in a holistic sustainability perspective. However, these projects require a gradual shift of their business models towards sustainable business models. In particular, performing quantitative sustainability analyses can help to overcome the traditional focus of business models on economic value and customers by defining wider costs and benefits for the environment and the society. This paper first provides a review of the state-of-the-art of sustainability analyses and business models for building renovation projects. Then, it proposes an analytic process based on the execution of quantitative sustainability examinations, as a support for the project proposition, creation, and capture of sustainable value in a multi-stakeholder perspective. The analytic process is applied to a case study that is the energy renovation project of a Norwegian single-family house, and several sustainability criteria are computed for three possible scenarios that are inclusive of different energy efficiency measures. The paper's findings can be relevant for both practitioners and academics who search for new approaches to embed quantitative analyses into the business context of building energy renovation projects. Furthermore, the findings can represent the groundwork for the possible operationalization of sustainable business in such projects, striving for a systematic execution of quantitative sustainability analyses as a key step towards sustainable business models.

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.

This paper provides a review of heat and ventilation measures that can be applied to ambitious energy renovation of detached houses in Nordic countries. In this review, requirements for solutions are defined. Key technologies are described and analysed in the context of renovation. The review focuses on strategies that are simple, cost-effective and robust, and can be transposed to the Norwegian context. The review revealed that a wider range of concepts and strategies than commonly used in Norway seem to be relevant. No solution or system appears to be an obvious and universal choice. A number of very different system solutions, with their pros and cons, are relevant, depending on the individual house and situation. Some combined heat and ventilation systems include hydronic space heating. This is however not common in Norwegian houses, and installing this is a major cost and intervention. Wood stoves, on the other hand, are regular, and can be used for peak heating. These factors seem to be crucial for the choice of system. Improved airtightness after renovation makes systematic ventilation measures necessary. Assumptions for occupant preferences and behaviour also seem to be important for choice of system. There are also differences in the commonly used HVAC concepts and strategies for renovation between the Nordic countries. These differences do not seem to be explained by climate only, and differences in building code may be part of the reason. A number of demonstration projects on ambitious energy upgrading are completed, but few of them have been systematically monitored and evaluated. Content from this work may be used under the terms of theCreative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd