Conference Agenda

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Session Overview
Session
Poster introductions 11: Extreme climate & climate adaptation
Time:
Thursday, 26/Aug/2021:
11:15am - 11:35am

Session Chair: Prof. Eva B Møller, Technical University of Denmark
Location: Room 4 - Room 015, Building: 116

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Presentations
11:15am - 11:18am

Building Integrated Photovoltaic/Thermal Collector for Arctic Residential Applications

Daniel J Baril, Andreas K Athienitis, Hua Ge

Concordia University, Canada

As the need for adequate indoor fresh air is more important than ever, strategies to ensure a steady supply while remaining energy efficient are required. In cold climates this can be done by Energy Recovery Ventilators (ERV), however in extreme cold conditions frequent frosting of the exchanger core reduces the effectiveness.

The objective of this study is to investigate the performance of an open loop air-based façade and roof building integrated photovoltaic/thermal collector (BIPV/T) system, to preheat the supply air for an ERV. The system was modeled in MATLAB using a 2-dimensional thermal network discretized using a finite difference method. Hourly values were calculated, including outlet temperature, heat recovered, and electrical energy generated. Air velocity and flow rates were varied to obtain maximum outlet air temperatures. It was found that compared to a roof integration, the façade produced more energy in the winter, late fall, and early spring, when frosting risks are the highest. The increased performance can be accredited to the smaller incident angle of the beam solar radiation on the façade during the periods of low solar altitude, and the ground reflected solar radiation from the many months of snow-cover.

Results showed that using a 19mm cavity created an air velocity of 0.8 m/s in the channel when using an airflow rate of 157 CFM supplied to the ERV. This configuration resulted in the highest outlet air temperature of the system; preheating air close to 20˚C during peak irradiance on a clear day in April. As well the clear sky daily energy production peaked in April and May, with 15kWh of electricity and 12kWh of heat recovered per day, respectively.

This investigation revealed that the BIPV/T can be a valuable method to preheat the supply air of ERV to ensure adequate indoor air quality while reducing energy usage.



11:18am - 11:21am

Preliminary assessment of the building design of a new test house in Nuuk, Greenland

Eva B Møller, Tove Lading

Technical University of Denmark, Denmark

Following an idea of how to create a new building style in the Arctic, DTU has established a single-family two-storey test house in Nuuk, Greenland. The main idea of the house was to have a relatively small heated area (app. 80 m²) but a split building envelope, where a ventilated space behind the rain screen in some areas can be used as a sunroom. In this way the inhabitants would have more space at times where the sun will heat the ventilated space; the summer will be prolonged without further energy costs. The concept of an unheated middle zone has been used in other projects as a “Greenhouse-concept”, but there was no experience from Greenland. Furthermore, the rain screen was made of polycarbonate with an U-value of 0,9 W/m2K and therefore different from other project with a similar concept.

Additionally, the layout was planned to be more in accordance with how the architects imagined Greenlanders would like to live than the traditional buildings where the layout is similar to European dwellings.

This paper describes the process of transforming the architectural ideas, originally presented at an international architectural exhibition, to a test building with inhabitants. It describes how the specific Arctic challenges changed the design several times and how compromises had to be made. Even during the building process new challenges occurred. Consequently, the paper points out difficulties in designing and building something untraditional in the harsh climate of Nuuk, Greenland.

The house is now inhabited and will be monitored for two years. During this period, the experience of the test family will be recorded.



11:21am - 11:24am

Hygrothermal performance of a massive stone wall insulated from the inside with hemp concrete – field measurements in cold climate

Markus Pau1, Targo Kalamees2,3, Urve Kallavus4

1Viljandi Culture Academy, University of Tartu, Estonia; 2Smart City Center of Excellence (Finest Twins), Tallinn University of Technology, Estonia; 3nZEB Research Group, Tallinn University of Technology, Estonia; 4Tallinn University of Technology, Department of Mechanical and Industrial Engineering, Ehitajate tee 5, Tallinn, Estonia

Improving the thermal comfort and energy performance of exterior walls of historic and traditional buildings is often only possible with interior thermal insulation. Hygrothermal performance and service life of interior insulation depends on material properties of the existing building envelope and new insulation materials as well on indoor and outdoor climate. The real structure and material properties of the existing exterior wall is usually the main unknown factor. Therefore field measurements with small mock-ups are helpful before the large-scale renovation. The stable of the historic manor complex will be renovated into a studio - visitor center, and the new expectations for the indoor climate and energy use caused the need to reduce the heat loss of the building. Hemp concrete is planned to use for reducing thermal transmittance and increase the surface temperature of external walls. Current study analyses by field measurements hygrothermal performance of interiorly insulated massive stone wall. Several different hemp concrete mixes were developed for the insulation. ~0.5m thick stonewall was insulated with two different types of hemp concrete. Temperature, humidity, and moisture content were measured over one year period. Results showed a very low drying rate. The external side of hemp concrete stays moist for a very long period. Also, wooden beams used to install hemp concrete will stay in moist areas for a long period. Before to large-scale renovations, it is necessary to find out the long term durability and performance of hemp concrete needs to be further investigated if it is to be in so moist environment. The temperature increase of the internal surface improved the thermal comfort indoors. Hemp concrete decreased the interior thermal mass and made the indoor temperature easily changeable.



11:24am - 11:27am

Assessing the climate change adaptation of building energy saving strategies over four European citiesclimate zones

Yuchen Yang1, Vahid Nik1,2,3

1Lund University, Sweden; 2Chalmers University of Technology; 3Queensland University of Technology (QUT)

In recent years, climate change has been widely recognized as a potential problem. The building industry is taking a variety of actions towards sustainable development and climate change mitigation, such as retrofitting buildings. More than mitigation, it is important to account for climate change adaptation and investigate the probable risks and limits for mitigation strategies. For example, one major challenge may become achieving low energy demand without compromising indoor thermal comfort during warm seasons. This work investigates the future energy performance and indoor thermal comfort of four European cities belonging to four different climate zones in Europe; Barcelona, Munich, Brussels, and Copenhagen. An ensemble of future climate scenarios is used, including thirteen climate scenarios considering five different general circulation models (GCM) and three representative concentration pathways (RCP 2.6, RCP 4.5 and RCP 8.5). Through simulating the energy performance of the representative buildings in each city and considering several retrofitting scenarios, this paper provides a comprehensive picture about the energy performance and indoor thermal comfort of the buildings for near-term, medium-term, and long-term climate conditions.



11:27am - 11:30am

Dependence of measured specific air leakage rate (qE50) on envelope pressure measurement position: a case study in an apartment building in winter conditions

Paul Klõšeiko1, Endrik Arumägi2, Jaanus Hallik2, Targo Kalamees2

1Tallinn University of Technology, Estonia; 2Smart City Center of Excellence (Finest Twins), Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia

Airtightness has become an important component in achieving ever stricter energy performance levels. However, airtightness measurements using blower door method are very much dependent on choices made by the specialist conducting the tests. One of them being the assessment of the nature of baseline pressure difference inside the building and suitable position of the measurement equipment.

Ideally, the test will be conducted without wind and stack effect which could disturb the envelope pressure measurements. To identify unsuitable conditions, ISO 9972 recommends that the pressure difference is measured at the lowest floor level and specifies the baseline pressure limits to comply with the standard. Unfortunately, these conditions seldom exist, especially in colder climates. This would make most of the year unsuitable for whole building measurements, while the alternative of conducting apartment-based measurements would give random results due to large share of interior walls, ceilings etc. This paper investigates the effect of using different measurement positions on the airtightness measurement results.

A 5-storey 15m tall residential building on the coastline of the Baltic sea was used as a case study and measured as a whole. Air pressure differences were simultaneously measured at different sides and heights of the building. Specific air leakage rates were then calculated based on pressure differences from different individual positions – designating different choices that the measurement specialist could make – and from the average of all of them. The whole building specific air leakage rates were also compared to measurements in a select number of apartments.

The paper proposes guidelines and measures to undertake in the case of unfavourable weather condtions in order to verify the compliance to preestimated air leakage criteria in apartment buildings.



11:30am - 11:33am

Utilization of Climate Files Predicting Future Weather in Dynamic Building Performance Simulation – A Review

Christian Nicolai Nielsen, Jakub Kolarik

Technical University of Denmark

As the climate is changing and buildings are designed with a life expectancy of 50+ years it is sensible to take climate change into account in the building design phase. Building performance simulations can be used to predict the impact of climate change on new and existing buildings with future weather files. Current simulation programs usually require one year of weather data with a temporal resolution of one hour which represents local climate conditions. However, both the temporal and spatial resolution of general circulation models is generally too coarse to be used for building performance simulation. Two general approaches to increase the resolution of climate models - statistical and dynamical downscaling have been developed. They exist in many variants and modifications. Due to the immense number of climate models, it is complicated to choose a representative ensemble of climate models and a conversion method to create future weather files well-suited for building performance simulation. This paper provides a comprehensive review of studies applying future weather data in building performance simulation. We highlight consistent and conflicting results using a world map as a tool to find hot spots of current studied locations. From the studies found it seems that it is a general trend to select the simplest methods, which often involves a compromise on selecting climate models. The review, to our knowledge being the first of its kind, provides a comprehensive overview of future weather application as well as critical insights in the model selection.



 
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