scholarly journals Tenant-based measured electricity use in 4 large office buildings in Tallinn, Estonia

2021 ◽  
Vol 246 ◽  
pp. 04001 ◽  
Author(s):  
Andrea Ferrantelli ◽  
Hans Kristjan Aljas ◽  
Vahur Maask ◽  
Martin Thalfeldt
Keyword(s):  
Input Data ◽  
Electricity Consumption ◽  
Internal Heat ◽  
Working Hours ◽  
Energy Performance ◽  
Office Buildings ◽  
Building Performance Simulation ◽  
Electricity Use ◽  
Internal Gain ◽  
Simulation Input

The energy performance assessment of buildings during design is usually based on energy simulations with pre-defined input data from standards and legislations. Typically, the internal gain values and profiles are based on EN 16798–1. However, studies have shown that the real electricity use of plug load and lighting varies more smoothly than in the profiles of EN 16798–1 where zero occupancy outside working hours is assumed. This might result in sub-optimal building solutions due to inadequate building performance simulation input data. The aim of this work is to structure and analyse data from a total of 196 electricity meters in 4 large office buildings in Tallinn, Estonia. Typically, 3 to 8 electricity meters were installed per floor with the consumption coming mainly from plug loads and electric lighting. The data had been gathered between the years 2016–2020 with either 1 or 24 hour time steps, depending on the building and the electricity meter. 3 out of the 4 buildings had an average normalized energy usage slightly below the modelling value calculated according to EN16798–1. Some office spaces stood out with an abnormally high electricity consumption, however, the 24-hour distributions were fairly compact, meaning quite steady consumption patterns. When looking at the dispersion of energy consumption per 24h, averaged over all given offices in a building, no outliers stood out, either. This means that there are not many days when the average consumption and internal heat gains of all offices were simultaneously well below the mean. Additionally, major events like holidays and the COVID19-induced lockdown show up well on the graphs, but also planned changes in occupancy can be seen.

scholarly journals Sensitivity Analysis of the Thermal Energy Need of a Residential Building Assessed by means of the EN ISO 52016 Simplified Dynamic Method

2020 ◽  
Vol 197 ◽  
pp. 02012 ◽  
Author(s):  
Franz Bianco Mauthe Degerfeld ◽  
Ilaria Ballarini ◽  
Giovanna De Luca ◽  
Mamak P. Tootkaboni ◽  
Vincenzo Corrado
Keyword(s):  
Sensitivity Analysis ◽  
Input Data ◽  
Dynamic Method ◽  
Great Influence ◽  
Internal Heat ◽  
Residential Building ◽  
Energy Performance ◽  
Set Point ◽  
Heating And Cooling ◽  
Correct Definition

The EN ISO 52016-1:2018 technical standard has introduced a new simplified dynamic method for the calculation of the building energy need for heating and cooling. This new procedure combines a low amount of input data required, as for the previous quasi-steady and dynamic simplified methods of the withdrawn EN ISO 13790 standard, with an increased accuracy, which would reduce the gap with detailed dynamic methods. This work is part of a broader research activity aimed at investigating the new simplified dynamic model and highlighting its strengths and weaknesses, in terms of accuracy and robustness. Specifically, the work addresses the parameters that have a great influence on the final results and the effects of uncertainties in input data. To this purpose both standard and tailored energy performance assessments have been applied, in particular in the first one a continuous operation period of the space heating system was supposed, and in the second one an intermittent operation system was chosen. A sensitivity analysis was also carried out to quantify the variation of the heating and cooling loads with the set-point temperature, the windows physical properties, the heat capacity and the thermal transmission properties of opaque components, as well as the occupancy related input parameters, such as the internal heat gains and the ventilation flow rate. The analysis was applied to a multi-unit residential building located in Rome and built in the first half of the 20th century. The results outline absolute relevance of the set point temperatures. The significance of occupant behaviour and the importance of the correct definition of the component thermal properties is also pointed out through the comparison between the standard and tailored assessments.

Impact of Internal Heat Gains on Building’s Energy Performance

2017 ◽  
Author(s):  
Vilūnė Lapinskienė ◽  
Violeta Motuzienė ◽  
Rasa Džiugaitė-Tumėnienė ◽  
Rūta Mikučionienė
Keyword(s):  
Energy Demand ◽  
Significant Proportion ◽  
Internal Heat ◽  
Working Hours ◽  
Energy Performance ◽  
Heating Season ◽  
Small Energy ◽  
Performance Simulation ◽  
Plug Loads ◽  
Heating Energy Demand

Internal heat gains from occupants, equipment and lighting contribute a significant proportion of the heat gains in an office space. Usage of ICT in offices is growing; on the other hand, their efficiency is also improving all the time. Increasing energy efficiency in buildings have led to the situation, when new, well insulated office buildings, with high internal gains within the working hours may cover low heating energy demand. Such buildings, even in heating dominated countries, such as Lithuania, often also suffer from overheating during the winter heating season. The paper presents the analysis of energy demand of the office building for various plug loads (ICT equipment) internal gains scenarios and demonstrates its influence on buildings energy performance. Simulation results enable to conclude, that when assessing sustainability and energy bills of the building, plug loads play a very important role. Meanwhile, assessing just energy performance influence is very small. Energy performance certification results show, that plug loads may influence energy performance label just for buildings corresponding A+ and A++ labels).

scholarly journals Impact of office tenants’ electricity use on the cost-optimal solutions in a cold climate

2021 ◽  
Vol 246 ◽  
pp. 05001
Author(s):  
Helena Kuivjõgi ◽  
Liina Laas ◽  
Andrea Ferrantelli ◽  
Martin Thalfeldt
Keyword(s):  
Input Data ◽  
Energy Use ◽  
Energy Performance ◽  
Cold Climate ◽  
Office Building ◽  
Optimal Solutions ◽  
Pv System ◽  
Electricity Use ◽  
The Cost ◽  
The Impact

The buildings’ energy performance requirements in Estonia are based on cost-optimality analysis according to the EPBD and pre-defined building performance simulation (BPS) input data from EN 16798-1:2019. Previous studies have shown that the real electricity use of office building tenants differs from the currently used input data in BPS in Estonia – less in total energy use, but more in the shape of the profiles. The aim of this work is to investigate what is the impact of these differences on the cost-optimal solutions, which are identified based on BPS and the self-consumption of the photovoltaic panel (PV) systems. This study describes the energy performance and construction cost analysis of a new office building in Tallinn, Estonia. BPS based on the EN 16798-1 and a model derived from measurements in a real building were conducted and cost-optimal building solutions identified. The variables were building envelope insulation thickness, air handling unit size and effectiveness, electrical lighting control principles and PV system nominal power. The calculated energy use of the building with the two different sets of input data differed significantly. However, the set of cost-optimal solutions identified with EN 16798-1:2019 input data had minor differences from the set of solutions identified with the more realistic model. The decrease of net present value over 20-year period for cost-optimal solution was 11-14 €/m2 compared to the designed building.The realistic office tenants’ electricity model increased the calculated self-consumption of the PV system from 95% to 100%.

scholarly journals Energy and Greenhouse Gas Savings for LEED-Certified U.S. Office Buildings

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 749
Author(s):  
John H. Scofield ◽  
Susannah Brodnitz ◽  
Jakob Cornell ◽  
Tian Liang ◽  
Thomas Scofield
Keyword(s):  
Greenhouse Gas ◽  
Energy Use ◽  
Energy Savings ◽  
Electric Energy ◽  
Building Energy ◽  
Energy Performance ◽  
Office Buildings ◽  
Ghg Emission ◽  
Site Energy ◽  
New Construction

In this work, we present results from the largest study of measured, whole-building energy performance for commercial LEED-certified buildings, using 2016 energy use data that were obtained for 4417 commercial office buildings (114 million m2) from municipal energy benchmarking disclosures for 10 major U.S. cities. The properties included 551 buildings (31 million m2) that we identified as LEED-certified. Annual energy use and greenhouse gas (GHG) emission were compared between LEED and non-LEED offices on a city-by-city basis and in aggregate. In aggregate, LEED offices demonstrated 11% site energy savings but only 7% savings in source energy and GHG emission. LEED offices saved 26% in non-electric energy but demonstrated no significant savings in electric energy. LEED savings in GHG and source energy increased to 10% when compared with newer, non-LEED offices. We also compared the measured energy savings for individual buildings with their projected savings, as determined by LEED points awarded for energy optimization. This analysis uncovered minimal correlation, i.e., an R2 < 1% for New Construction (NC) and Core and Shell (CS), and 8% for Existing Euildings (EB). The total measured site energy savings for LEED-NC and LEED-CS was 11% lower than projected while the total measured source energy savings for LEED-EB was 81% lower than projected. Only LEED offices certified at the gold level demonstrated statistically significant savings in source energy and greenhouse gas emissions as compared with non-LEED offices.

scholarly journals A Fundamental Study on the Development of New Energy Performance Index in Office Buildings

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2064
Author(s):  
Jin-Hee Kim ◽  
Seong-Koo Son ◽  
Gyeong-Seok Choi ◽  
Young-Tag Kim ◽  
Sung-Bum Kim ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Energy Requirement ◽  
Energy Performance ◽  
Office Buildings ◽  
Light Transmittance ◽  
Wall Structure ◽  
Fundamental Study ◽  
Future Studies ◽  
U Value ◽  
The Impact

Recently, there have been significant concerns regarding excessive energy use in office buildings with a large window-to-wall ratio (WWR) because of the curtain wall structure. However, prior research has confirmed that the impact of the window area on energy consumption varies depending on building size. A newly proposed window-to-floor ratio (WFR) correlates better with energy consumption in the building. In this paper, we derived the correlation by analyzing a simulation using EnergyPlus, and the results are as follows. In the case of small buildings, the results of this study showed that the WWR and energy requirement increase proportionally, and the smaller the size is, the higher the energy sensitivity will be. However, results also confirmed that this correlation was not established for buildings approximately 3600 m2 or larger. Nevertheless, from analyzing the correlation between the WFR and the energy requirements, it could be deduced that energy required increased proportionally when the WFR was 0.1 or higher. On the other hand, the correlation between WWR, U-value, solar heat gain coefficient (SHGC), and material property values of windows had little effect on energy when the WWR was 20%, and the highest effect was seen at a WWR of 100%. Further, with an SHGC below 0.3, the energy requirement decreased with an increasing WWR, regardless of U-value. In addition, we confirmed the need for in-depth research on the impact of the windows’ U-value, SHGC, and WWR, and this will be verified through future studies. In future studies on window performance, U-value, SHGC, visible light transmittance (VLT), wall U-value as sensitivity variables, and correlation between WFR and building size will be examined.

scholarly journals Modeling Energy Efficiency Performance and Cost-Benefit Analysis Achieving Net-Zero Energy Building Design: Case Studies of Three Representative Offices in Thailand

2021 ◽  
Vol 13 (9) ◽  
pp. 5201
Author(s):  
Kittisak Lohwanitchai ◽  
Daranee Jareemit
Keyword(s):  
High Efficiency ◽  
Energy Gap ◽  
Cost Benefit ◽  
Building Design ◽  
Energy Performance ◽  
Office Buildings ◽  
Zero Energy ◽  
Zero Energy Building ◽  
Investment Cost ◽  
High Investment

The concept of a zero energy building is a significant sustainable strategy to reduce greenhouse gas emissions. The challenges of zero energy building (ZEB) achievement in Thailand are that the design approach to reach ZEB in office buildings is unclear and inconsistent. In addition, its implementation requires a relatively high investment cost. This study proposes a guideline for cost-optimal design to achieve the ZEB for three representative six-story office buildings in hot and humid Thailand. The energy simulations of envelope designs incorporating high-efficiency systems are carried out using eQuest and daylighting simulation using DIALux evo. The final energy consumptions meet the national ZEB target but are higher than the rooftop PV generation. To reduce such an energy gap, the ratios of building height to width are proposed. The cost-benefit of investment in ZEB projects provides IRRs ranging from 10.73 to 13.85%, with payback periods of 7.2 to 8.5 years. The energy savings from the proposed designs account for 79.2 to 81.6% of the on-site energy use. The investment of high-performance glazed-windows in the small office buildings is unprofitable (NPVs = −14.77–−46.01). These research results could help architects and engineers identify the influential parameters and significant considerations for the ZEB design. Strategies and technical support to improve energy performance in large and mid-rise buildings towards ZEB goals associated with the high investment cost need future investigations.

scholarly journals Reported Behavioural Patterns of Electricity Use among Low-Income Households in Makhanda, South Africa

2021 ◽  
Vol 13 (13) ◽  
pp. 7271
Author(s):  
Uzziah Mutumbi ◽  
Gladman Thondhlana ◽  
Sheunesu Ruwanza
Keyword(s):  
South Africa ◽  
Low Income ◽  
Sustainable Consumption ◽  
Electricity Consumption ◽  
Developed Countries ◽  
Electricity Use ◽  
Behavioural Patterns ◽  
Education Levels ◽  
Basic Services ◽  
Low Income Households

Households consume up to 20% of overall electricity consumption globally; hence, they are important role players in efforts towards promoting sustainable consumption. Research on electricity use behaviour is important for informing intervention strategies; however, relative to developed countries, research on this subject is lacking in developing countries where electricity access is limited. In South Africa, electricity use behaviour among poor neighbourhoods remains little studied and understood. This study was carried out among low-income households in Makhanda, South Africa, characterised by high poverty and unemployment rates, low education levels, and limited access to basic services. Using a self-reporting approach, electricity use behaviour of low-income households was assessed against a list of common household electricity use actions. A survey of 297 households was conducted. The findings show mixed results, with households reporting both good electricity use behaviour (e.g., cooling down hot food before refrigeration and using washing machines on full load) and wasteful actions (e.g., leaving appliances on standby). Our results show that electricity use behaviour was influenced by socio-psychological values including universalism, benevolence, hedonism, and power. Some of the reported electricity behavioural patterns are consistent with those previously reported among high-income households. The theoretical and practical implications of these results are discussed.

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