Karen Byskov Lindberg

Analysis of grid interaction indicators in net zero-energy buildings with sub-hourly collected data

This paper aimed to contribute to the discussion about the role of net zero-energy buildings (ZEBs) or nearly ZEBs in future energy systems, from the perspective of the resulting import/export interaction with the surrounding energy grid (commonly named grid interaction (GI)). This investigation analyses three buildings with measured data at sub-hourly time resolution. The goal of this paper was to quantify the effect of using high-resolution data (one or a few minutes) versus hourly resolution in the GI analysis of buildings with an on-site generation system. A limited set of quantitative GI indicators have been selected: the generation multiple, the dimensioning rate and the connection capacity credit. Additionally, this paper presents graphical representations describing in an intuitive way the yearly or daily variation of the indicators. Some general trends have been identified and the usefulness of the selected indicators is demonstrated. Findings show conclusively that sub-hourly analysis will give more accurate information. Differences between peak values measured with hourly and sub-hourly time resolution can be significant. If detailed GI analysis at the individual building level is required, one should consider going for detailed sub-hourly analysis.

Modeling the Effects of Variable Tariffs on Domestic Electric Load Profiles by Use of Occupant Behavior Submodels

Emerging infrastructure for residential meter communication and data processing carries the potential to control household electrical demand within local power system constraints. Deferral of load control can be incentivized through electricity tariff price structure, which can in turn reshape a daily load profile. This paper presents a stochastic bottom-up model designed to predict the change in domestic electricity profile invoked by consumer reaction to electricity unit price, with submodels comprising user behavior, price response, and dependency between behavior and electric demand. The developed models are used to analyze the demand side management potential of the most relevant energy consuming activities through a simulated German household demonstrating that in the given scenario 8% of the annual electricity demand is shifted, leading to a 35€ annual saving. However, a 7% higher than average peak load results from the structure of the tariff signal modeled herein. A discussion on selected aspects for tariff design for categories of typical household appliances is included.

Hourly electricity load modelling of non-residential passive buildings in a nordic climate

Detailed knowledge of electricity demand is essential for power system planning and operation. EUs 20-20-20 targets will increase the development of more energy efficient buildings as all new buildings shall be “nearly zero energy buildings” by 2020. The result from this ambition is that so-called passive buildings and nearly-net-zero-energy-buildings (nZEB), with lower energy demand, or even onsite power generation, will significantly change the way buildings are integrated in the power system. System operators must consequently prepare for changes in load profiles. However, the knowledge on the aggregated impact of nZEBs is so far limited because the actual number of such buildings is still very small. This paper contributes to this knowledge gap by estimating the aggregated effect on electricity demand profiles. The load modelling is based on a statistical approach deriving hourly electricity load profiles of non-residential buildings based on measurements of 100 buildings. The profiles will be used as basis in further work to study the impact of a large rollout of ZEBs on the power system.

Large scale introduction of Zero Energy Buildings in the Nordic power system

The objective of this paper is to investigate the effects of a large deployment of Zero Energy Buildings (ZEB) in Norway on utilization of hydropower in 2030. A ZEB is a building with low energy demand, which produces on an annual basis, as much renewable energy as its energy consumption, and is considered as one of the key elements to reach EUs 20-20-20 goals. The simulations are conducted using a detailed power market model of the Nordic countries, i.e. Denmark, Norway, Sweden and Finland. The findings show that ZEBs mainly influence the optimal operation of the power system in two ways, 1) through their lower electricity demand, and 2) through their on-site PV production. Hydro power contributes to 50 % of the total power generation in the Nordic countries. Because PV generates power before the spring flooding occurs, the power producers go lower in the hydro reservoirs, thus lowering the spillage of water, which increases the hydro power production with 0,5 %. Further, the introduction of ZEBs leads to 4-6 TWh lower coal power production, reduced power price, and 17-26 TWh increased export from the Nordic countries.