Category Archives: Engineering

Energy, Energy transition, Engineering, heat transfer, HVAC, Science

New publication on energy storage

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This paper investigates how a simulated room’s energy and temperature performance are affected if its underfloor heating control is modelled with increasing detail. Experiments were performed to develop and calibrate an empirical model of wax motor and to calibrate the valve curve. These models were used to implement and test the On/Off and proportional-integral (PI) control processes at various levels of modelling detail. Controllers were implemented by gradually adding optimized control parameters, signal delay, calibrated valve curve, signal modulation, and actuator modelling. The On/Off control dead band and PI parameters exhibited the largest impact, reducing energy use (1%–5%) and temperature fluctuations (ca 1 K). Modulating the PI output signal increased temperature fluctuations to the same amplitude as On/Off with 0.5 K dead band, increasing space heating demand by 1.3%. The wax actuator counted for less than 1%; however, it increased time delays to maximally 7 min and remarkably changed the mass flows.

Parts , T M , Ferrantelli , A , Naar , H , Thalfeldt , M & Kurnitski , J 2023 , ‘ Wax actuator’s empirical model development and application to underfloor heating control with varying complexity of controller modelling detail ‘ , JOURNAL OF BUILDING PERFORMANCE SIMULATION . https://doi.org/10.1080/19401493.2023.2201818

Energy, Energy policy, Energy transition, Engineering, geothermal energy

New paper published! Energy efficiency, energy transition, emissions reduction

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Our newly published paper demonstrates how choosing different #energytransition policies at the European level can radically affect renovation rates, costs, CO2 #emissionsreduction, and #energyefficiency. MDPI TalTech – Tallinn University of Technology Aalto University

https://www.mdpi.com/1882366

Abstract

Energy renovations of the building stock are a paramount objective of the European Union (EU) to combat climate change. A tool for renovation progress monitoring is energy performance certificate (EPC) labelling. The present study tested the effect of different EPC label classifications on a national database, which comprises ~25,000 EPC values from apartment buildings, detached houses, office buildings, and educational, commercial, and service buildings. Analysing the EPC classes labelling resulting from four different EU methods, we estimated the annual renovation rates, costs, energy savings, and CO2 emissions reduction that would affect the national building stock if each of them was adopted, to fulfil the European Climate Target Plan by the year 2033. The ISO 52003-1:2017 two-point and one-point methods determined a very uneven distribution of renovation rates, from 0.45% to ~9%. Conversely, the Directive 15% recently proposed in COM/2021/802 with uniform rates determined smaller differences and standard deviation, not pushing renovations above 3.70%, namely a rate that once fine-tuned can stimulate realistic, yet effective renovation campaigns. The major differences in renovation rates provided by the studied methods show the need for a harmonized strategy such as the Directive proposal to enable achievement of European targets.

Keywords: Energy Performance Building Directive (EPBD); Energy Performance Certificates (EPC); carbon emissions; energy efficiency; statistical analysis; European Green Deal

Energy, Engineering

New paper published on IEEE: “Evaluating the Energy Readiness of National Building Stocks Through Benchmarking”

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In our new paper, just published in IEEE Access, by analysing nearly 35000 EPC certificates covering 11 building categories in Estonia, we

  • Characterised the time evolution of EPC classes
  • Evaluated the impact of incentives pre/post-renovations
  • Created benchmarking tables to be used in detailed auditing
  • Estimated the year when each building category should reach the ZEB status

The paper is open access and free to download at: https://ieeexplore.ieee.org/abstract/document/976354863548

Abstract:

Evaluating the #energy performance of existing buildings is critical for improving the efficiency and resilience of the building stock as a whole. The importance of this information holds at different scales, both locally and at the national and international levels. A major problem arises from the difficulty in obtaining information from existing buildings; often, the only available data are the yearly consumption per unit area, typically corresponding to the energy performance certificate (EPC). This paper shows how to address concerns of practical relevance with a limited number of variables by examining an EPC national database (including the major cities of Tallinn, Pärnu, Tartu, and others) that provides only EPCs, construction/renovation year and heated area. Through a systematic statistical investigation of nearly 35 000 EPCs of educational, office, commercial and other building typologies, we i) characterise the time evolution of EPC classes, ii) evaluate the impact of incentives pre/post-renovations, and iii) create benchmarking tables that allow comparisons of a specific building with the existing stock to identify representative buildings for detailed auditing. The readiness of the Estonian building stock could thus be evaluated by linear fitting. All new and renovated buildings are estimated to achieve the zero-energy building (ZEB) status by 2050; remarkably, for some categories, this will occur already in the present decade if the identified linear trends persist. Additionally, we investigated whether the #COVID-19 pandemic has affected building stock readiness by comparing pre- and post-2020 ZEB year fit estimations. Contrary to what was expected, the change in working habits affected some building types only marginally, while the national regulations played a prominent role. Detached private houses exhibited a pronounced worsening in readiness, while the educational and entertainment sectors benefited from specific energy labelling remodulations.

Energy, Engineering, heat transfer, HVAC, Science, Weather

New paper on energy data mining now published

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Office Building Tenants’ Electricity Use Model for Building Performance Simulations
https://www.mdpi.com/1996-1073/13/21/5541

Abstract

Large office buildings are responsible for a substantial portion of energy consumption in urban districts. However, thorough assessments regarding the Nordic countries are still lacking. In this paper we analyse the largest dataset to date for a Nordic office building, by considering a case study located in Stockholm, Sweden, that is occupied by nearly a thousand employees. Distinguishing the lighting and occupants’ appliances energy use from heating and cooling, we can estimate the impact of occupancy without any schedule data. A standard frequentist analysis is compared with Bayesian inference, and the according regression formulas are listed in tables that are easy to implement into building performance simulations (BPS). Monthly as well as seasonal correlations are addressed, showing the critical importance of occupancy. A simple method, grounded on the power drain measurements aimed at generating boundary conditions for the BPS, is also introduced; it shows how, for this type of data and number of occupants, no more complexities are needed in order to obtain reliable predictions. For an average year, we overestimate the measured cumulative consumption by only 4.7%. The model can be easily generalised to a variety of datasets.
Keywords: building simulation; office buildings; energy performance; energy modelling; HVAC; analytical modelling; statistical analysis

Energy, Engineering, geothermal energy, heat transfer, HVAC, Science

New paper on geothermal energy published

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Our latest paper introduces a tabulated tool that aids in the early design of geothermal systems, by providing estimates of the system’s efficiency according to the chosen energy piles field configuration and heat pump sizing.

Direct link: https://doi.org/10.1016/j.enbuild.2020.110178

The paper can be downloaded FOR FREE for 50 days at this link:
https://www.sciencedirect.com/science/article/pii/S037877882031152X?dgcid=author

Abstract

Geothermal systems are often employed for both the heating and cooling of sustainable constructions. Energy piles (U-shaped heat exchangers inserted into the foundation piles) are widely included in these installations, whose performance is usually estimated by means of complex, time-consuming simulations already at an early design stage.
Here we propose a simple methodology, where a hand calculation tool provides the condenser yield per pile meter, ground area yield and demand covered by the heat pump by specifying only building heat load and geometric characteristics of the energy piles field. Our tool is tested by assuming 20 years of operation in a hall-type commercial building in a cold climate. A validated IDA-ICE parametric study couples the heat pump evaporator operation with heat transfer processes between energy piles and soil. Various system configurations are considered and thermal storage in the soil is included.
We find that the expected yield is not directly proportional to pile separation, while a smaller extraction power is favoured. Thermal storage in the soil is also confirmed to be critical. Besides our specific quantitative results, our practical guideline is qualitatively general and can be extended to any given building type and climate.

Energy, Engineering, heat transfer, HVAC, Science

New paper published: “A novel method for calculating heat emitter and controller configuration setpoint variations with EN15316-2”.

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We published a new article! Highlights of the paper, available at https://doi.org/10.1016/j.jobe.2020.101387:

  • A novel method for the accurate calculation of total setpoint variations.
  • Effects of real system losses are better represented than with component assessment
  • Simulations of annual energy consumption compare losses for new and old building.
  • A common platform to compare emission efficiency under standardised conditions.

Abstract:
Estimating heat emission losses of heating systems is an important task of energy efficiency assessments in buildings. However, the present international standards do not specify how emission losses should be calculated or measured for different emitter and control system configurations. Aiming to fill this gap, here we propose a method for computing the temperature setpoint variations by addressing the heat distribution throughout a room with space heat emitters. This general and exact procedure enables the calculation of product category-specific setpoint variations for different types of heat emitters, accounting for the overall heat balance in the enclosure and including the cross-correlations of each component. Our method complements the procedure presented in the Standard EN15316-2, making it possible to compute emission losses as product-specific values of setpoint variations instead of tabulated values. As the main finding of the study, the calculation process is defined for a European Reference Room that allows an accurate and transparent evaluation of total setpoint variations. These are computed for specific products from measured vertical stratification and control parameters, by means of an annual IDA ICE simulation model of the reference enclosure. Applying the method to an annual energy performance simulation for an old and a new building in Strasbourg shows that emission losses are compensated by a total setpoint variation of respectively up to 2.00 °C and 1.20 °C, corresponding to an increase in total heating energy usage of up to 22% and 20%.

Energy, Engineering, geothermal energy, heat transfer, Physics, Science

Special Issue “Energy Performance and Indoor Climate Analysis in Buildings” available for free download

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Our Special Issue with MDPI titled “Energy Performance and Indoor Climate Analysis in Buildings” (18 papers) is available for free download here: https://www.mdpi.com/books/pdfview/book/1828
#Engineering #energy #Sustainability #Science #civilengineering

Energy, Engineering, geothermal energy, heat transfer, Physics, Science

Special Issue “Energy and Technical Building Systems – Scientific and Technological Advances” now published

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Our special issue with @MDPIOpenAccess “Energy and Technical Building Systems – Scientific and Technological Advances” (10 papers published) is now fully and freely available in pdf at https://www.mdpi.com/journal/energies/special_issues/energy_and_built_environment #Engineering #energy #energyefficiency #Sustainability #HVAC

Energy, Engineering, geothermal energy, heat transfer, Science

Sector coupling in urban districts – an opportunity towards decarbonisation

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Sector coupling is a concept referring to the electrification of end-use sectors (e.g. heating and transport); it aims at increasing the share of renewable energy (solar, hydro, geothermal, wind, bioenergy, waste heat…) in these sectors.
In practice, this is a strategy “to provide greater flexibility to the energy system so that decarbonisation can be achieved in a more cost-effective way”.

The EU has committed under the Paris Agreement to make an effort to keep the global temperature rise below 2ºC, and the decarbonisation of the energy system can be crucial to this purpose. Sector coupling then becomes a key player for the EU “policy objective of shifting from our current highly centralised and mainly fossil fuel-based energy system to a more decentralised, energy efficient and renewable energy-based energy system”.

The quoted paragraphs are taken from an official European Parliament document on Sector Coupling, which you can find at the link below. I strongly encourage everybody interested in energy systems to read it (especially those who are critical towards the usage of wind and solar energy…yes, they still do exist!).
https://www.europarl.europa.eu/RegData/etudes/STUD/2018/626091/IPOL_STU(2018)626091_EN.pdf