Conference Agenda

Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

 
 
Session Overview
Session
Session 25: Energy performance & consumption
Time:
Thursday, 26/Aug/2021:
4:00pm - 5:30pm

Session Chair: Prof. John Grunewald, TU Dresden
Location: Room 3 - Room 013, Building: 116

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Presentations
4:00pm - 4:15pm

The effect of weighting factors on income-related energy inequalities: The case of Sweden’s new building code

Jenny von Platten1,2, Mikael Mangold1, Kristina Mjörnell2,3

1Division of Built Environment, RISE Research Institutes of Sweden; 2Department of Building and Environmental Technology, Faculty of Engineering, Lund University; 3Business and Innovation area Sustainable Cities and communities, RISE Research Institutes of Sweden

To ensure building construction with low heating demand, efficient use of sustainable energy carriers, and neutrality between heating technologies, Sweden recently introduced weighting factors (WFs) for different energy carriers that are now used in Energy Performance Certificates (EPCs). As EPC ratings are gaining increased influence in Swedish energy policy and regulation, with recent examples of buildings’ EPC rating acting as base for imperative regulatory requirements, the introduction of WFs is likely to have significant effects on how policy and regulations are distributed in the multifamily building stock. As residents often are directly or indirectly affected by policy that either impose or trigger measures to be undertaken in their building, the aim of this paper is to analyse how WFs affect the assessed energy performance of buildings in different income groups. The results show that overall, reduced energy performance from WFs was more prevalent in high-income areas than in low-income areas. However, although the total number of buildings with the lowest EPC ratings was reduced after introducing WFs, the resulting income distribution among worst-performing buildings was more skewed towards low-income households than before introducing WFs. As imperative regulatory requirements previously have targeted worst-performing buildings, these results indicate that energy-related inequalities in the housing stock have become more prominent and should be considered as to not disproportionately burden low-income residents in the energy transition of the housing stock.



4:15pm - 4:30pm

Investigating the relationship between residential AC, indoor temperature and relative humidity in Indian dwellings

Rajat Gupta1, Anu Antony1, Vishal Garg2, Jyotirmay Mathur3

1Low Carbon Building Research Group, School of Architecture, Oxford Brookes University, United Kingdom; 2IIIT Hyderabad, India; 3MNIT Jaipur, India

Residential electricity consumption (REC) in India has tripled in the past two decades accounting for 24% of the overall electricity consumption during 2018-19. Residential air conditioning (AC) usage is a one of the largest contributors of REC. This paper investigates the relationship of residential AC use with indoor temperature and relative humidity (RH) using concurrent time-series monitoring data gathered in eight dwellings for the summer and monsoon seasons. Contextual data about the dwelling (physical) and household characteristics were gathered using face-to-face interview based surveys. The dwellings are located in Hyderabad representing composite climate of India. The mean daily electricity consumption was found to be higher in summer (11.5kWh) possibly due to the higher usage of AC (because of higher ambient conditions) as compared to 6.5kWh/day during monsoon season. Binary logistic regression identified the trigger indoor temperature and RH at which AC was likely to be switched on in the summer as 29 °C - 31.9 °C for indoor temperature and 36-38.9% RH. In the monsoon season AC was predicted to come on sooner at 26°C-28.9°C but at higher RH range of 59-61.9%. These empirical findings can be used to reduce residential cooling energy demand through smart management of AC in Indian dwellings.



4:30pm - 4:45pm

Domestic hot water system in residential buildings: production, distribution and taping energy loss. Monitoring campaign in three Danish single family houses.

Anna Marszal-Pomianowska, Rasmus Lund Jensen, Michal Pomianowski, Olena Kalyanova Larsen, Jacob Scharling Jørgensen, Sofie Sand Knudsen

Department of the Built Environment, Aalborg University, Denmark

While energy use for building space heating has been continuously decreasing over the last decades, the energy need for domestic hot water (DHW), i.e. production, distribution, circulation, has remained relatively constant. Consequently, the share of the DHW energy used in the total energy balance of buildings is becoming more and more prominent, e.g. typical Danish dwellings dedicate between 20% to 35% of their total energy need to DHW production and operation, and this share increases up to 40 to 50% in low-energy buildings. This tendency is presumably similar in other developed and developing countries.

Therefore, the aim of this study is to provide thorough knowledge into the area by measuring the DHW consumption in three single-family houses in Denmark directly connected to district heating system. The measurements included the whole DHW system, i.e. preparation point (DHW heat exchanger), distribution system (DHW pipes) and end-use points (all draw-off points in the house). The detailed measurements with data sampling frequency of 8Hz provided a comprehensive and dynamic insight in the energy losses at different parts of the DHW system.

The investigations showed that energy loss at the production point, which indicate also the efficiency of DHW heat exchanger, varies between days. It is correlated with the tapings profile during the day, i.e. the share of short (duration < 15 sec) and long (duration > 60 sec) tapings. As presented in Fig 1. data collected on one selected day in House 1 indicate that 8% of energy is lost due to heat exchanger efficiency, 15% is lost from the DHW distribution pipes (only part of this heat is utilized for space heating) and 3% is related to waste water and waiting time for comfort temperatures, e.g. during showering.



4:45pm - 5:00pm

A probabilistic approach to include the overall efficiency of gas-fired heating systems in urban building energy modelling

Katia Ritosa1, Ina De Jaeger1,2,3, Dirk Saelens1,2, Staf Roels1

1Building Physics and Sustainable Design, Department of Civil Engineering, KU Leuven, Belgium; 2EnergyVille, Belgium; 3Flemish Institute for Technological Research (VITO), Belgium

Urban building energy modelling has an essential role in the estimation of energy demand at urban or neighbourhood scales. However, current modelling methods have limitations in reproducing realistic gross energy usage. Due to the scarcity of available data sources, often over-simplified approaches are chosen to fill the gap between, what in reality would be, a smart-meter reading and the heat demand. Although it is theoretically possible to simulate all components of the heating system in detail, such extensive approach significantly increases the computational effort, prohibiting a large scale probabilistic analysis. As an alternative, a simplified data-driven approach can be used. Assuming the simulated heat and domestic hot water (DHW) demand is already computed for buildings in an observed district, it is possible to allocate the overall losses in post-processing. In the proposed approach the thermal losses are attributed to each of the components of the heating system as efficiencies, as they depend on the energy demand. The current work incorporates overall efficiency estimation for six most occurring gas-fired heating systems configurations in Flemish single-family dwellings. Those six configurations include two types of production units (condensing and non-condensing boilers) each paired with three versions of DHW sub-systems (direct, indirect and none). For all systems’ configurations, efficiencies of emission, distribution, production, control and storage components are taken into account. The efficiency of the production unit is modelled most in detail as it includes the load-dependency. Moreover, the nominal production efficiency is sampled from normal distributions for the chosen heating system and assigned to each dwelling in order to reproduce the diversity in the actual building stock. In the presentation of the proposed simplified approach, it is assured that sufficient variation in size, insulation quality and occupancy schedules is present in the observed dwellings.



5:00pm - 5:15pm

A novel concept for energy-efficient floor heating systems with minimal hot water return temperatures

Kevin Michael Smith, Nan Hu, Dorte Skaarup Østergaard, Svend Svendsen

Department of Civil Engineering, Technical University of Denmark, Denmark

The study proposed and investigated a new concept for hydronic floor heating in dwellings with the aim of reducing hot water temperatures toward a more robust and energy efficient operation. Modern heating systems often rely on low return temperatures to improve operation efficiencies through reduced heat losses from return pipes, greater utilisation of condensation heat from boiler flue gases or from the increased COP of heat pumps. Our study investigated the potential of using an apartment heating substation (or ‘flat station’) to supply space heating through two mixing loops using hot water supply temperatures of 30 °C to bathrooms and 24 °C to all other rooms. The concept sought to minimise hot water supply temperatures to ensure low return temperatures. In the first iteration of the concept, the return water from the bathrooms was cascaded to the other rooms to heat these rooms and provide further cooling of the hot water. The calculated energy-weighted return temperature under this original concept was 25.62 °C for the example case of a new energy-efficient apartment building. However, there was limited potential to utilise the cascaded coupling, so considering the complexity of its configuration and control, the authors simplified the proposed concept to two mixing loops without a cascade coupling. The calculated return temperature with the updated concept was 25.7 °C. The control of the floor heating included some aspect of self-regulation because the heat transfer strongly depended on the indoor temperature. Based on the results of this preliminary investigation, the concept may provide a robust and energy-efficient option for configuring floor-heating systems in situations that rely on low hot water return temperatures.



5:15pm - 5:30pm

Establishing Requirements to Thermal Energy System Resilience for Cold/Arctic Climates

Alexander Zhivov1, Richard Liesen1, Brianna Morton1, Brandy Diggs-McGee1, Bjorn Oberg1, Angela Urban1, Emmette Leffel2, Dayne Broderson3

1US Army Engineer Research and Development Center, United States of America; 2Alaska Thermal Imaging, United States of America; 3University of Alasks, Fairbanks, United States of America

Thermal energy systems resilience is especially important for extreme climates, such as arctic or tropical environments. While metrics and requirements for availability, reliability and quality of power systems have been established, similar metrics and requirements for thermal energy systems are not well understood. This paper addresses requirements to resilience for thermal energy systems comprised of energy conversion, distribution and storage components. The paper includes results of a study conducted to better understand the level of reliability required for energy supply systems that will be capable of supporting environmental conditions required for the facility’ mission, comfort of people and sustainment of a building in arctic environments under predominant threat scenarios and the modeling analysis that is compared and calibrated to the experimental data. A reliable building model allows us to predict the maximum time available to repair the heat supply system before the building needs to be evacuated, when damage is done to equipment or facilities critical to the building operations, or when damage is done to the building itself. This will provide guidance to building managers on evacuation and sustainment procedures for buildings in arctic climates that are affected by fuel or electrical disruptions.



 
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