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Especially for wooden wall constructions, ventilated rain-screen walls have been used for many decades to prohibit moisture-induced damage. The air gap behind the façade cladding provides drainage, enhances ventilation, and thus facilitates drying of wetted façade components. The conditions in the air gap behind different cladding materials, however, are still an object of research. In the presented study, the interim findings after more than two years of ongoing measurements in the air gap behind different cladding materials of a zero-emission office building in the high-latitude city of Trondheim, Norway are presented. The results provide valuable insight into the temperature conditions in the air gap of ventilated claddings in order to determine the in-use conditions of building materials and develop improved testing schemes. The results indicate that the air and surface temperature in the air cavity of the walls is strongly influenced by the solar radiation incidence on the facades. Both the highest and lowest values were observed on the roof with 81 °C and -21.9 °C, respectively, at the back side of the building integrated photovoltaic modules, resulting in a total temperature range of almost 103 °C.

One of the 17 Sustainable Development Goals proclaimed in the 2030 Agenda for Sustainable Development by the United Nations is Sustainable Cities and Communities. In the view of urbanization and a rising world population, the ambition is to create and transform cities into climate-resilient, safe, healthy, climate-friendly, and livable environments for its citizens. This thesis aims to contribute to this goal in the context of Norwegian climate conditions. For that, multiple approaches and methodologies are used. First, an extensive literature study is conducted to synthesize the characteristics of the urban climate, focus areas, and research gaps from scientific publications addressing cold and polar climate regions. Second, numerical tools including computational fluid dynamics (CFD) and building performance simulation (BPS) are used to create models for studying the effect of different climates and design scenarios particularly with regard to people’s outdoor thermal comfort and building energy demand. Field measurements of relevant climate variables from a network of fixed and temporary weather stations are used to provide input and validation data for the numerical models predicting the local climate conditions in an urban neighborhood (microclimate). Finally, a coupling methodology for CFD and BPS is presented that allows investigation of the energy demand of different floors of a high-rise building considering vertical temperature gradients derived from CFD simulations. For most of the thesis work, the Gløshaugen campus of the Norwegian University of Science and Technology which is currently under redevelopment served as a case study. From the literature review, it was found that the urban climate in cold climate regions is strongly affected by the presence of the urban heat island (UHI). Mostly, observational methods were used and only 22 % of the reviewed studies used numerical tools to replicate, predict or investigate different scenarios of the urban climate. The numerical simulations in this thesis show that solar access is key for improving the outdoor thermal comfort in urban areas during the cool and cold seasons in Norway. Also, wind sheltering proves to be an effective measure, however, only at relatively high wind speeds and on a smaller scale than solar access. Changing the material properties of the urban surface in a dense urban environment only presents a negligible effect on outdoor thermal comfort during cool or cold weather conditions. Moreover, solar access is favorable in buildings, as in Norwegian climate conditions, south-oriented, unshaded windows can lead to more useful solar energy gains than detrimental energy losses, on an annual basis. The benefit of wind sheltering to lower a building’s energy demand is found to be small, as new buildings according to the Norwegian building regulations get increasingly airtight. Furthermore, it is shown that especially during a summerly heat wave in Norway, the cooling energy demand and indoor overheating can be reduced effectively with vast urban greening compared to a concrete-sealed urban surface. While in summer the effects of different material compositions of the urban surface on the microclimatic conditions are very distinct, they are less pronounced in autumn and marginal in winter during the investigated conditions. Resulting from the proximity to the urban surface, the effect is strongest in the lower floors of a building. This thesis underlines the importance of including urban microclimate in the planning process of buildings and neighborhoods, as well as giving it a stronger role in study syllabi. It shows that numerical modeling is a valuable resource for the understanding of the urban (micro)climate and gives detailed examples for its application. The results are intended to provide useful knowledge for researchers and practitioners in architecture, building engineering, and urban planning, as well as decision-makers in public authorities.

Den raske urbaniseringen har ført til dannelse av komplekse urbane morfologier som har resultert i temperaturøkning i byene sammenlignet med nærliggende landlige områder. Med urbanisering følger bygningene og bygningene med mye energi. Derfor er det et viktig fokus for studier i dag å redusere energibehovet til en bygning. En av måtene er å studere klimaet på mikroskala nivå. Generell praksis i dag er imidlertid å ta klimadataene fra en typisk meteorologisk værstasjon uten å ta hensyn til det lokale klimaet der bygningen skal bygges. I denne forbindelse evaluerer denne studien virkningen av mikroklima på energibehovet ved bruk av simuleringsverktøy for bygningsenergiytelse (IDA ICE). NTNU Gløshaugen campus er valgt til studietomten og Sentralbygg 1 blir tatt som et representativt bygg. Bygningen er modellert i IDA ICE og simulert ved hjelp av forskjellige klimatiske data. For det første brukes Værnes klima i simulering. Det oppnådde resultatet blir sammenlignet med resultatene fra klimaet i Gløshaugen. Det viser at det er en betydelig forskjell i energibehov mens du bruker mikroklimatiske data. Det er en reduksjon på rundt 8,4% av energibehovet når du bruker værdataene fra Gløshaugen. Videre brukes CFD-genererte værdata i en uke hver sommer og høst. To case-scenarier vurderes for studien, det ene, basissituasjon hvor vegetasjon, fortau og materialer blir vurdert som den er, og andre ikke-vegetasjonsscenariet der vegetasjonen fjernes og erstattes av betong. Resultatene viser at basissaksscenariet har lavere energibehov om sommeren på grunn av at ikke-vegetasjonsscenariet resulterte i ytterligere kjølebehov. På toppen av det sammenlignes klimadataene fra Værnes og Gløshaugen med studieforskjeller når det gjelder temperatur, varmegradedager, vindhastighet og solstråling. Gløshaugen-campus viser omtrent 2˚C høyere temperatur enn Værnes. Varmegradedagene knyttet til Værnes værdata er 11% høyere enn Gløshaugen. Basert på resultatene og funnene, blir det gitt relevante anbefalinger for den fremtidige energidesignen i bygninger. The rapid urbanization has led to formation of complex urban morphologies which have resulted in increase of temperature in cities as compared to nearby rural areas. With urbanization comes the buildings and buildings consume high amount of energy. Therefore, reducing the energy demand of a building is a major focus of study today. One of the ways is through study of the climate at micro-scale level. However, the general practice today is to take the climate data from a typical meteorological weather station without considering the local climate where the building is to be built. In this regard, this study evaluates the impact of microclimate on building energy demand using building energy performance simulation tool (IDA ICE). NTNU Gløshaugen campus is selected for the study site and Sentralbygg 1 is taken as a representative building. The building is modelled in IDA ICE and simulated using different climatic data. Firstly, the climate of Værnes is used in simulation. The obtained result is compared with the results from the climate of Gløshaugen. It shows that there is a significant difference in energy demand while using the microclimatic data. There is a reduction of about 8.4% of energy demand while using the weather data from Gløshaugen. Further, the CFD generated weather data is used for one week each in summer and autumn. Two case scenarios are considered for the study, one, the base case scenario where the vegetations, pavements and materials are considered as it is, other the no-vegetation scenario where the vegetation is removed and replaced by concrete. The results show that the base case scenario has lower energy demand in summer case due to the fact that the no-vegetation scenario resulted in additional cooling demand. On top of that, the climate data from Værnes and Gløshaugen are compared to study differences in terms of temperature, heating degree days, wind velocity and solar radiation. The Gløshaugen campus shows about 2˚C higher temperature than that of Værnes. The heating degree days associated with Værnes weather data is 11% higher than that of Gløshaugen. Based on the results and findings, relevant recommendations are made for the future energy design in buildings.