One of the most effective actions for reduction of energy loss through the building envelope is to optimize the thermal performance, area and localization of the transparent components in the façade in order to obtain minimal heat losses and optimal solar gains.

When considering the thermal performance of these transparent components, one should consider, not only heat loss (or gains) caused by thermal transmission, but also the beneficial effects of incident solar radiation and hence reduced demand for heating and artificial lighting.

This study presents calculations for a range of windows as part of a building where the coupled effects of incident solar radiation and thermal transmission heat losses are accounted for in terms of a net energy balance for the various solutions. Effects of varying thermal transmittance values (U-values) are studied in connection with solar heat gain coefficients.

Three different rating methods have been proposed and applied to assess the energy performance of several window configurations. It has been found that various rating methods give different energy saving potentials in terms of absolute figures. Furthermore, it has been found that windows, even with existing technology, might outperform an opaque wall in terms of heating and cooling demands.

Published in Journal papers

The main purpose of this book, Hygrothermal, Building Pathology and Durability, is to provide a collection of recent research works to contribute to the systematization and dissemination of knowledge related to construction pathology, hygrothermal behaviour of buildings, durability and diagnostic techniques and, simultaneously, to show the most recent advances in this domain. It includes a set of new developments in the field of building physics and hygrothermal behaviour, durability approach for historical and old buildings and building pathology vs. durability. The book is divided in several chapters that are a resume of the current state of knowledge for benefit of professional colleagues, scientists, students, practitioners, lecturers and other interested parties to network.

Published in Books

Building integrated photovoltaics (BIPVs) are photovoltaic materials that replace conventional building materials in parts of the building envelopes, such as roofs or facades, i.e. the BIPV system serves dual purposes, as both a building envelope material and a power generator. Hence, it is important to focus on the building envelope properties of a BIPV system in addition to energy generation performance when conducting experimental investigations of BIPVs. The aim of this work was to illustrate challenges linked to the building envelope properties of a BIPV system, and to develop and evaluate relevant methods for testing the building envelope properties of BIPV systems.

A sample roof area with two BIPV modules was built and tested in a turnable box for rain and wind tightness testing of sloping building surfaces with the aim of investigating the rain tightness of the BIPV system, and observing how it withstood wind-driven rain at large-scale conditions. The BIPV sample roof went through testing with run-off water and wind-driven rain with incremental pulsating positive differential pressure over the sample at two different inclinations. The BIPV sample roof was during testing constantly visually monitored, and various leakage points were detected. In order to prevent such water penetration, the steel fittings surrounding the BIPV modules should ideally be better adapted to the BIPV modules and constricted to some extent. It is however important to maintain a sufficient ventilation rate simultaneously.

Published in Journal papers

A case study of a Norwegian detached house is used to evaluate the sustainability of two nearly zero energy renovation strategies. Energy demand, life cycle cost and home qualities are assessed as sustainability indicators. The Façade renovation strategy is an energy upgrade of the façade supplemented with high renewable energy production on site. The Ambitious renovation strategy is a total building envelope upgrade using passive house components and a lower on site renewable energy production. Both renovation strategies result in a 50–85% reduction of the heating requirement depending on the renewable energy production. The sustainability assessment was done as an iterative process including qualitative and quantitative parameters. The Ambitious renovation strategy is more costly than the Façade alternative over a 30 year period. However, homeowners do not base their decisions to renovate strictly on cost evaluations and homeowner categories influence the assessment. The Façade strategy is suitable for homeowners that do the retrofit themselves and homeowners prioritizing to keep the existing architectural qualities of their house. The Ambitious strategy is more suitable for the homeowners seeking to change the aesthetics of their home as well as for the homeowners emphasizing the overall technical performance after renovation.

Published in Journal papers

Building Integrated Photovoltaic (BIPV) is an important source of renewable energy production for Zero Emission Buildings, even in Norwegian climate. In the planned Powerhouse 1 building at Brattøra in Trondheim the idea to reach a zero emission building level is to use PVs as a roofing material covering the entire roof. Challenges and questions raised in the design process of this building have motivated the work reported here.

Published in Reports

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