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
Category Archives: Engineering
Sector coupling in urban districts – an opportunity towards decarbonisation
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
Presentation at the Trondheim conference now available for download
A short and coincise presentation I gave in Trondheim (Norway) on 7.11.19, which summarizes the parametric study reported in the conference paper (see the link below).
https://doi.org/10.1088/1755-1315/352/1/012011
Here is the presentation:
https://www.researchgate.net/publication/337111301_Parametric_study_for_the_long_term_energetic_performance_of_geothermal_energy_piles
Conference paper on geothermal energy now published
Here you can download the pdf (open access):
https://iopscience.iop.org/article/10.1088/1755-1315/352/1/012011
I will give the talk next week at the 1st Nordic nZEB+ conference in Trondheim, Norway!
Abstract:
Geothermal energy constitutes an important renewable resource that will become increasingly prominent in future constructions. A common method of extraction and usage consists of installing, inside the foundation piles of buildings, U-shaped heat exchangers called ”energy piles”.
In this paper such installations are addressed by means of a full parametric study, performed for a hall-type commercial building in a cold climate. By computing the transient heat transfer between energy piles and ground for a period of 20 years, guidelines for a preliminary sizing of the geothermal system as a whole are provided. These are valid for this specific building and climate, for a clay-type soil and without assuming thermal storage.
A highly nonlinear behaviour of the expected yield in relation to pile separation and evaporator extraction power is observed. Furthermore, 15m-long piles are found to be more efficient than those with double length, a smaller extraction power seems to be more favourable and differences in the pile diameter have little impact for heat transfer. A geothermal system sizing guide, which is useful for a preliminary quantitative test prior to any installation, is introduced. Even though our specific results are valid only for a commercial hall-type building in Finland, our procedure is qualitatively general and can be utilized for any given building type and climate zone.
New website layout
Following the Taoist aim at simplicity, I have redesigned the website with a simpler layout, and cleared up all the pages from redundancies.
Hopefully now everything is more accessible, go and have a look!
Two conference papers now published
The two conference papers on #energy efficiency in buildings I presented last May at the conference CLIMA 2019, #Bucharest are now published, with open access:
New paper explaining the crack patterns on the surface of heated wood
Our new paper on heated wood seems to confirm our model for a phenomenon that remained unexplained for a few decades.
https://onlinelibrary.wiley.com/doi/abs/10.1002/fam.2722?af=R
Abstract:
When a flat sample of medium density fibreboard (MDF) is exposed to radiant heat in an inert atmosphere, primary crack patterns suddenly start to appear over the entire surface before pyrolysis and any charring occurs. Contrary to common belief that crack formation is due to drying and shrinkage, it was demonstrated for square samples that this results from thermomechanical instability. In the present paper, new experimental data are presented for circular samples of the same MDF material. The sample was exposed to radiant heating at 20 or 50 kW/m2, and completely different crack patterns with independent eigenmodes were observed at the two heat fluxes. We show that the two patterns can be reproduced with a full 3‐D thermomechanical surface instability model of a hot layer adhered to an elastic colder foundation in an axisymmetric domain. Analytical and numerical solutions of a simplified 2‐D formulation of the same problem provide excellent qualitative agreement between observed and calculated patterns. Previous data for square samples, together with the results reported in the present paper for circular samples, confirm the validity of the model for qualitative predictions and indicate that further refinements can be made to improve its quantitative predictive capability.
New paper on energy efficiency published
A new paper on the energy efficiency of buildings (here, ice hockey halls) is now published!
Title:
Energy analysis in ice hockey arenas and analytical formula for the temperature profile in the ice pad with transient boundary conditions
Abstract:
The energy efficiency of ice hockey arenas is a central concern for the administrations, as these buildings are well known to consume a large amount of energy. Since they are composite, complex systems, solutions to such a problem can be approached from many different areas, from managerial to technological to more strictly scientific. In this paper we consider heat transfer processes in an ice hockey hall, during operating conditions, with a bottom-up approach based upon on-site measurements. Detailed heat flux, relative humidity and temperature data for the ice pad and the indoor air are used for a heat balance calculation in the steady-state regime, which quantifies the impact of each single heat source. We also solve the heat conduction equation for the ice pad in transient regime, and obtain a general analytical formula for the temperature profile that is suitable to practical applications. When applied to the resurfacing process for validation, it shows good agreement with an analogous numerical solution. Since our formula is given with implicit initial condition and boundary conditions, it can be used not only in ice hockey halls, but in a large variety of engineering applications.
https://www.tandfonline.com/eprint/kKUN792Us3j7QVgTpMpB/full?target=10.1080/17512549.2019.1615549
New research paper on geothermal energy now published
Our paper discussing the usage of geothermal energy for heating buildings is now published. You can download the full version from the publisher at the following webpage:
Paper on energy efficiency in buildings now published
Our paper “A combined analytical model for increasing the accuracy of heat emission predictions in rooms heated by radiators” is now published on the Journal of Building Engineering. Here is the link to the pdf (free download for the next 50 days):
https://www.sciencedirect.com/science/article/pii/S235271021831413X?dgcid=author
Abstract:
The efficiency of heat emitters plays an important role in the improvement of building energy performance, especially in the context of system and product comparison. In particular, it can be directly related to thermal comfort via the operative temperature that is effectively sensed by the users.
For the first time in the literature, in this paper we develop a combined analytical model for room and radiator that computes directly the heat output required to maintain a specific operative temperature. The total heat balance of the enclosure is used to accurately quantify and compare the heat emission losses of different radiator types via an analytical calculation of the operative temperature. This determines the efficiency of a selection of panel radiators with different surface temperature, radiation fraction and number of panels, which were tested in a chamber conforming to the EN 442-2 standard.
Additionally, we assess the related annual energy consumption in different climates by carrying out annual simulations in old (without heat recovery) and new (with heat recovery) building types located in Tallinn, Estonia and Strasbourg, France. In the new building we find a similar performance for all the radiators. In the old building however, one radiator outperforms the other two with up to 1.38% lower annual energy consumption, due to smaller rear losses and higher thermal comfort provided by the larger front panel surface.
Quantum Prana - The Dark Matter Guitar 