Additional Insulation Research Articles

Zero-energy log house – Future concept for an energy efficient building in the Nordic conditions

The current target to decrease the energy consumption of buildings is important as the residential sector consumes a significant part of the energy over the energy chain. Another driver is to reduce greenhouse gas emissions to tackle global warming. Renewable energy sources and technical solutions should play the main role in this pursuit. In this paper, a zero-energy log house in southern Finland is analyzed in detail. The analysis consists of the design, construction, and practical use during the years 2017–2019. The objective of the study is to show that a highly energy efficient log house can be achieved in Nordic conditions without additional insulation by utilizing renewable energy sources and energy technical solutions. The energy efficiency of the house is clearly higher than defined in the national nearly zero-energy building (nZEB) regulations. The house has a plus energy classification and carbon negative emissions for the energy. The operational cost of electricity is on both sides of zero.

Efficacy of warming systems in mountain rescue: an experimental manikin study

Mountain accident casualties are often exposed to cold and windy weather. This may induce post-traumatic hypothermia which increases mortality. The aim of this study was to assess the ability of warming systems to compensate for the victim’s estimated heat loss in a simulated mountain rescue operation. We used thermal manikins and developed a thermodynamic model of a virtual patient. Manikins were placed on a mountain rescue stretcher and exposed to wind chill indices of 0 °C and − 20 °C in a climatic chamber. We calculated the heat balance for two simulated clinical scenarios with both a shivering and non-shivering victim and measured the heat gain from gel, electrical, and chemical warming systems for 3.5 h. The heat balance in the simulated shivering patient was positive. In the non-shivering patient, we found a negative heat balance for both simulated weather conditions (− 429.53 kJ at 0 °C and − 1469.78 kJ at − 20 °C). Each warming system delivered about 300 kJ. The efficacy of the gel and electrical systems was higher within the first hour than later (p < 0.001). We conclude that none of the tested warming systems is able to compensate for heat loss in a simulated model of a non-shivering patient whose physiological heat production is impaired during a prolonged mountain evacuation. Additional thermal insulation seems to be required in these settings.

Acoustic performance of composite sandwich panels for building floors: Experimental tests and numerical-analytical simulation

Composite sandwich panels have been increasingly considered in structural applications due to their lightweight, high strength, environmental resistance, and ease of assembly. Yet, since transmission loss phenomena are usually governed by mass, their low weight renders composite sandwich panels potentially inefficient in terms of acoustic performance, a subject that has received little attention in the past. This paper presents experimental, numerical and analytical investigations about the acoustic performance of composite sandwich panels used in building construction. Standard airborne and impact sound transmission tests are performed on a full-scale composite sandwich panel, designed for structural application in building floors, and their acoustic performance is compared with the applicable code requirements. In the numerical study, a finite element model is developed to simulate the airborne sound transmission. The analytical study assesses the applicability of the reciprocity theorem to such panels. The obtained results confirmed the overall low acoustic performance of lightweight composite sandwich panel floors and pointed out the need for additional sound insulation measures. The numerical simulations presented good agreement with the experimental data, following the overall development of the experimental transmission loss curve, and predicting the dip associated with the coincidence effect. The application of the reciprocity theorem to the sandwich panel floors was validated with the experimental results and allowed for an accurate prediction of the impact sound pressure level based on the numerical results of the airborne sound reduction.

The Use of Fly Ash in the Production of Concrete and Products Based on it

Reftinskaya state district power plant owned by Enel company and located in Russia produces up to 5 million tons of fly ash and slag annually when burning multi-ash coal of the Ekibastuz basin. A new system of dry ash removal works at the power plant; it includes the laying system of wet ashes and slags on the dump and the discharge system from the silo storage facility up to 1 million tons of ash per year. The chemical-mineral and grain composition data, properties and their correspondence to Russian standard 25818 in order to use ash in the production of concrete and products based on it are presented. The experience of production and application of autoclaved aerated ash concrete of reduced density is considered. It is shown that fly ash of Reftinskaya state district power plant is an effective substitute for quartz sand in the technology of cellular concrete. Its application opens up additional opportunities for aerated concrete with a density of 300-400 kg/m3 production. To optimize the structure and properties it is proposed to introduce an additive of natural gypsum in the amount of 3-5 % of the mass of dry components into the autoclave aerated concrete. The produced aerated ash concrete had a thermal conductivity of 0.075-0.100 W/m∙K which allows it to be used for erection of single-layer enclosing structures without additional insulation. Fly ash can also be used as part of heavy and fine-aggregate concrete replacing a part of Portland cement and sand. The addition of ash in an amount of up to 25 % by weight of cement improves the workability and reduces the demixing of the concrete mix. Ash introduction up to 10 % increases the compressive strength of concrete at an early time and after 28 days of normal hardening, an increase of it up to 25 % decreases the compressive strength, reduces the conductivity, but increases the shrinkage of concrete. The optimum ash content up to 100 kg/m3 for steamed concrete and not more 50 kg/m3 for normal hardening concrete. Compliance with the optimal composition and technological parameters of the production of concrete structures using ash enables to produce concrete of F200-F300 grade by frost resistance.

Three-dimensional self-floating foam composite impregnated with porous carbon and polyaniline for solar steam generation

A promising approach to resolving insufficient freshwater resources is utilizing solar energy for steam generation. Although various types of photothermal conversion materials have been developed, there are still some obstacles, such as complicated system structure fabrication and low energy utilization, that severely hinder their practical application. Herein, we designed and produced a self-floating porous carbon/polyaniline foam (PCPF) evaporator via impregnating melamine foam with porous carbon generated following the bottom-up pyrolytic method and polyaniline, followed by thermal treatment, for efficient solar steam generation. The PCPF obtained with a porous carbon (PC) to polyaniline (PAN) mass ratio of 3:5 (PCPF-3) exhibited a rich pore structure, good hydrophilicity, low thermal conductivity (0.0413 W m−1 K−1), and excellent light absorption (96.1%). Our results show that, without additional thermal insulators, the evaporation rate of PCPF-3 reached 1.496 kg m−2 h−1, and the photothermal conversion efficiency reached 87.3% under one sun irradiation. Furthermore, it also exhibited good durability and desalination performance. This type of environmentally friendly, low-cost, and stable photothermal conversion material could be used in water treatment and seawater desalination.

The influence of architectural and construction parameters of residential buildings on energy efficiency in Russian Federation

The article discusses the dependence of the energy saving class of a residential multi-apartment building on various architectural and construction parameters. The study was conducted on the example of a building model for 36 cities of the Russian Federation in various climatic conditions. The calculation of the energy saving class was carried out according to the method of Building Code 50.13330.2012 «Thermal insulation of buildings». The analysis of this technique in relation to the architectural and construction components of the building is given. It is shown that the traditional approach to the design of residential buildings without the use of additional energy saving measures allows to achieve an energy saving class at level «B» (above -30 % of the base value) regardless of the height of the building. A significant change in the energy saving of the building with a different glazing-to-wall ratio is shown. It is proved that the additional insulation of the building envelope does not lead to an effective increase in energy saving. The calculation showed that heat recovery using a mechanical ventilation system is an important factor in increasing the energy efficiency of residential buildings.

Improvement of a scraper heat exchanger for pre-heating plant-based raw materials before concentration

When heating liquid and paste-type products, enterprises in the food industry commonly use scraper heat exchangers, which, given their high heat treatment intensity, make it possible to retain the original properties of the treated raw materials. Most heat exchangers demonstrate an unstable stabilizing effect: the vapor pressure ‒ the temperature that leads to damage to raw materials, under conditions of significant energy- and metal capacity. It is possible to eliminate these drawbacks by using a temperature-stable flexible film resistive electric heater of the radiating type as a heater in an improved scraper heat exchanger. We have proposed applying a hinged blade with a cutting edge (with a reflective heating surface) as a stirring element of the heat exchanger to obtain the uniform distribution of a product layer thickness at the working surface and to additionally heat by the blade's reflective surface. The heat exchanger can be supplemented with a cooling shell with ring channels to pass the refrigerant, which is placed on the outer surface of the non-thermally insulated flexible electric heater. Such a solution provides the possibility of cooling to −15 °C and it simultaneously serves the additional air thermal insulation in the absence of the carrier in it. We have determined the uniformity of heat flow distribution over the heating surface of the model design of the improved unit (60.3...60.5 °C) and at the reflective surface of the hinged blade with a cutting edge (60.0...60.3 °C). The total thickness of a liquid layer has been established depending on the shaft rotation frequency of the proposed hinged blade with a cutting edge: at 50 min –1 – 1–2.65 mm, at 350 min –1 –1.5 mm, compared with a standard hinge blade (a layer thickness is from 5.0 mm to 1.5 mm), in terms of product consumption W=50 l/h. The improved scraper heat exchanger is characterized by a 1.48-time decrease in the specific energy consumption (170.4 kJ/kg), used to heat a product volume unit, compared to the heater with a steam shell – 252.6 kJ/kg. The research result is the confirmed efficiency of using the improved scraper heat exchanger, as well as its proposed structural scheme

Influence of Additional Insulation Block on Melt-Crystal Interface Shape in Directional Solidification System for Growing High Quality mc-Silicon Ingot: a Simulation Investigation

We have carried out the numerical simulation for DS system for growing multi-crystalline silicon (mc-Si) ingot with different size additional insulation blocks. Thermal Stress, melt-crystal interface shape and dislocation density are the main factors that can determine the efficiency of solar cells. Thermal stress and dislocation density can be controlled by controlling the heat dissipation from the crucible. The simulation results revealed that the effective controll of melt-crystal interface shape has been obtained by the suitable additional insulation block in DS system. At particular size of insulation block (3 cm) the optimal melt-crystal interface shape, von Mises stress, Maximum shear stress and maximum principal stress have been established during the solidification process which can enhace the mc-Si ingot quality, for photovoltaic application.

Energy Performance of a High-Rise Residential Building Using Fibre-Reinforced Structural Lightweight Aggregate Concrete

The increasing need for eco-friendly green building and creative passive design technology in response to climatic change and global warming issues will continue. However, the need to preserve and sustain the natural environment is also crucial. A building envelope plays a pivotal role in areas where the greatest heat and energy loss often occur. Investment for the passive design aspect of building envelopes is essential to address CO 2 emission. This research aims to explore the suitability of using integral-monolithic structural insulation fibre-reinforced lightweight aggregate concrete (LWAC) without additional insulation as a building envelope material in a high-rise residential building in the different climatic zones of the world. Polypropylene and steel fibres in different dosages were used in a structural grade expanded clay lightweight aggregate concrete. Physical and thermal properties of fibre reinforced structural LWAC, normal weight concrete (NWC) and bricks were measured in the lab. The Autodesk@Revit-GBS simulation program was implemented to simulate the energy consumption of a 29-storey residential building with shear wall structural system using the proposed fibre-reinforced LWAC materials. Results showed that energy savings between 3.2% and 14.8% were incurred in buildings using the fibre-reinforced LWAC across various climatic regions as compared with traditional NWC and sand-cement brick and clay brick walls. In conclusion, fibre-reinforced LWAC in hot-humid tropical and temperate Mediterranean climates meet the certified Green Building Index (GBI) requirements of less than 150 kW∙h∙m−2. However, in extreme climatic conditions of sub-arctic and hot semi-arid desert climates, a thicker wall or additional insulation is required to meet the certified green building requirements. Hence, the energy-saving measure is influenced largely by the use of fibre-reinforced LWAC as a building envelope material rather than because of building orientation.

Improvement of Indoor Thermal Environments through Green Refurbishment

This study investigates the performance of the “green refurbishment” of existing buildings. Two ordinary rooms in an existing building were chosen for examination. Refurbishment measures such as additional insulation, high-performance glazing, and air-tightening were applied to the control room. Temperature and electricity use were monitored to identify heating performance in winter and then compared with a baseline. The results of the field tests showed that green refurbishment significantly improved heating performance. Lowered heating load and electricity use with increased airtightness were also verified through building performance simulations. The empirical investigation suggests a predictive model to obtain indoor minimum temperatures as a function of outdoor temperature swings.

Mechanical and Thermal Performance Characterisation of Compressed Earth Blocks

The present research is focused on an experimental investigation to evaluate the mechanical, durability, and thermal performance of compressed earth blocks (CEBs) produced in Portugal. CEBs were analysed in terms of electrical resistivity, ultrasonic pulse velocity, compressive strength, total water absorption, water absorption by capillarity, accelerated erosion test, and thermal transmittance evaluated in a guarded hotbox setup apparatus. Overall, the results showed that compressed earth blocks presented good mechanical and durability properties. Still, they had some issues in terms of porosity due to the particle size distribution of soil used for their production. The compressive strength value obtained was 9 MPa, which is considerably higher than the minimum requirements for compressed earth blocks. Moreover, they presented a heat transfer coefficient of 2.66 W/(m2·K). This heat transfer coefficient means that this type of masonry unit cannot be used in the building envelope without an additional thermal insulation layer but shows that they are suitable to be used in partition walls. Although CEBs have promising characteristics when compared to conventional bricks, results also showed that their proprieties could even be improved if optimisation of the soil mixture is implemented.

The effect of the building blind area heat insulation on heat losses through the floor on the ground

The relevance of the problem under studying is the appearance of non-traditional heating insulation structures of the floor on the ground, that can not be subject to calculations of heat losses using the existing methods. The purpose of this article is to find out the average characteristic heat transfer resistances in the design zones adopted in the Russian Federation for thermal protection of the floor on the ground by heat insulating the blind area of the building. Factors essential for possible elimination of condensation on the junction of the floor and the exterior walls were evaluated, as well as the possible maintenance of the floor temperature at the border of the serviced area not below specified values. The method of investigation is the annual calculation of unsteady thermal regime of flooring with the soil massive by finite difference method according to the implicit scheme. As the results we can state a significant impact of the type of soil on the heat loss through the ground floor, an insignificant impact of the width and thickness of the insulated building blind area. The most critical for the possibility of using the blind area heat insulation is the practical inability to provide acceptable temperatures of the floor at the wall-to-floor junction and on the border of the serviced zone. The main conclusion is that the heat insulation of the building blind reaches its goals at the room temperature of 10 °C. But it needs additional small heat insulation of the floor on the ground itself at a room temperature of 20°C and 30°C.

Cooling of Windings in Electric Machines via 3-D Printed Heat Exchanger

This article presents a novel use of three-dimensional printed direct winding heat exchangers (3-D-DWHX) to improve the thermal management of the stator in high power density electric machines. The 3-D-DWHX is in direct contact with the stator windings, enabling high continuous current densities. The use of dielectric polymer for the heat exchanger allows direct contact with the windings without an additional insulation material. By occupying the otherwise unused space between double layer concentrated windings, there is no significant impact on the electromagnetic design, and a smaller machine can be realized. The result is an increased continuous power rating and power density of electric machines. The polycarbonate-aluminum flake 3-D-DWHX was validated in a nonencapsulated motorette test, achieving a continuous current density of 20.4 ARMS/mm2 for a hotspot temperature of 148 °C. Finite element analysis shows that the same design, when encapsulated, can achieve 33.3 ARMS/mm2 current density with a hotspot temperature of 195 °C, corresponding to a continuous specific power of 11.8 kW/kg.

Exploring the trade-off in life cycle energy of building retrofit through optimization

Building retrofit is considered as a vital step to achieve energy and climate goals in both Europe and Sweden. Nevertheless, retrofitting solutions based merely on reducing operational energy use can increase embodied energy use, mainly due to altering the existing trade-off between the two. Considering this trade-off is vitally important, especially for retrofitting buildings located in cold climate regions, as reduction of operational energy use to meet standards of energy-efficient buildings may require a deep retrofitting that can considerably increase the embodied energy and thus be unfavorable from a Life Cycle Energy (LCE) perspective. This article presents a case study in which multi-objective optimization was used to explore the impact of a wide range of retrofitting measures on the aforementioned trade-off for a building in Sweden located in a subarctic climatic zone. The studied building was a typical 1980s multi-family residence. The goal was to explore and compare the optimal retrofitting solution(s) for the building, aiming to achieve Swedish energy-efficient building standards (i.e. new-build and near-zero energy standards). The results of the optimization indicated that (1) use of additional insulation in walls and roof, (2) replacement of existing windows with more energy-efficient ones, and (3) change of traditional mechanical extract ventilation to heat recovery ventilation are the primary and optimal retrofitting measures to fulfill the new-build Swedish energy standard and achieve highest LCE savings. However, to fulfill more far-reaching operational energy savings, application of additional retrofitting measures was required, increasing the embodied energy use considerably and resulting in lower LCE savings compared to the optimal retrofitting solution that only reached the Swedish new-build energy standard. The LCE difference between the optimal retrofitting solutions that fulfilled the new-build standard and the strictest near-zero (passive house) standard was 1862 GJ, which is equivalent to almost four years of operational energy use for the original building. This indicates that there is a limit to the reduction of operational energy use when retrofitting existing buildings, beyond which additional reductions can considerably increase the embodied energy and thus be unfavorable in terms of LCE use.

Thermal Conductivity of Olive Cake Compost (OCC) as Affected by Moisture and Density: An Experimental and Mathematical Modeling

The behaviors of bioactive compounds treating gaseous pollutants in biofilters and in the compost used as soil amendment and in green roof buildings are controlled by their thermal properties. There is a lack of information on thermal conductivity of olive cake compost (OCC), K as affected by water content and bulk density. Thermal conductivities (K) of 40 samples of (OCC) were determined experimentally at bulk densities (400–950 kg/m3) and moisture contents (10%–90%) using a single thermal probe method. The results showed that thermal conductivity increased linearly as water content, and bulk density increased and with a decrease in air filled porosity. Simple linear relationships were developed between compost thermal conductivity and dry bulk density and the degree of saturation. The experimental values were close to those reported recently for leaf compost and green roof soils. The compost at water content of 90% showed the highest thermal conductivity (K) of 0.60 W/m.k, which indicate that compost, can be used as good cheep insulator in geothermal heat storage application and as an additional echo-friendly insulation layer in green roof building which might be considered as a good means of passive energy saving there.

Energy savings and overheating risk of deep energy renovation of a multi-storey residential building in a cold climate under climate change

Here, we analyse final and primary energy savings and overheating risk of deep energy renovation of a Swedish multi-storey residential building of the 1970s under climate change and consider overheating control measures to reduce cooling demand and risk of overheating. The energy-efficiency measures include additional insulation to basement walls, exterior walls, and attic floor as well as improved energy-efficient windows and doors, balanced ventilation with heat recovery (VHR), lighting, household appliances as well as water taps and shower heads. The future climates are based on the representative concentration pathways scenarios. We find that implementing improved energy-efficient windows and doors, VHR and additional insulation to external walls give significant final and primary energy savings for space heating. The total operation final and primary energy use decrease averagely by 58% and 54%, respectively when all the measures are cumulatively applied under both current and future climate scenarios. Efficient household appliances and lighting as well as appropriate overheating control measures significantly reduce cooling demand and risk of overheating. The indoor air temperature and overheating risk as well as the final energy savings are influenced by the considered climate scenarios.

The importance of adjusting the heating system after an energy-retrofit of buildings in a sub-Arctic climate

There is a need to improve the understanding and the knowledge of energy efficiency measures for residential buildings in sub-Arctic climate regions. This paper presents an investigation of two identical multi-family residential buildings in the sub-Arctic climate of northern Sweden, before and after renovation. During the renovation, additional insulation of the external walls and new windows were installed in one building, while the other building retained its original envelope.The energy usage data for the past four heating seasons were collected, including data from before and after the renovation. Detailed thermal indoor climate data were gathered for specific months. The data from the two separate buildings showed that the renovation did not result in a significant improvement in energy usage. Prior to the renovation, the energy usage data showed a difference of 2–3% in the heat supply between the two buildings, and this difference persisted after the renovation. On the other hand, the indoor air temperature was raised. The renovated building had an indoor air temperature which was 2 °C higher than the not yet renovated building.IDA ICE models were constructed and validated with the measured data to investigate how a lower indoor air temperature would affect the energy usage and indoor thermal climate. The models showed that with a reduction in the indoor air temperature by 2 °C after the renovation, the thermal climate would maintain an acceptable level according to PMV/PPD standards, and would result in a 13–14% reduction of the heat supply during the cold months. With an annual reduction of 15%, the heat supply could be reduced by 270 MWh per year for the whole area where the buildings are located. This clearly demonstrates the importance of adjusting the heating system after an energy efficiency measure has been performed.

Thermal bridge effect of vertical diagonal tie connectors in precast concrete sandwich panels: an experimental and computational study

The purpose of this work was to quantify the thermal bridge effect of vertical diagonal tie connectors in precast concrete sandwich panels (PCSPs). Special interest was in cases where the use of rigid insulation (e.g. PIR) would leave air gaps between insulation boards and diagonal ties, thus intensifying the thermal bridge. A climate chamber experiment using 5 different joint types was performed to gather reference data for CFD model validation. In the experiment, natural convection was observed in joints where no additional insulation was used, i.e. in air cavities. Significantly larger heat fluxes were measured in these cavities compared to insulated joints. The thermal bridging effect was evaluated for a typical PCSP (thermal transmittance without thermal bridges U = 0.11 W/(m²·K)) using CFD software taking into account 3D heat conduction and convection. Simulation results indicate that diagonal ties without adjacent air cavities increased the average thermal transmittance (U-value) of the envelope by 8%, diagonal ties with a 6 mm air cavity – 19...33% and diagonal ties with a 10 mm air cavity – 45...56%. In conclusion, it was found that the joints in insulation caused by diagonal ties affect the overall thermal performance of the building envelope significantly when efforts are not made to fill the air cavities around the connectors.

Heat exchange simulation in energy zones of a rotarykiln with change of heat resistance of the body

The object of research is high-temperature thermal units – rotary kilns. Rotary kilns are used in various industries. The specified equipment has high energy consumption, which is due to the operating conditions of the kiln units in compliance with a number of technological requirements for thermal conditions. At the same time, the problem of high energy intensity is aggravated by the low level of useful energy resources. One of the most problematic places is the thermal and operational characteristics of rotary kilns, as well as the use of lining with increased thermal resistance.Physical and mathematical models are used. It is proposed to calculate a rotary kiln for the production of cement with a size of 5x185 m and a capacity of 75 t/h. A mathematical model is obtained for computer simulation of technological processes in rotary cement kilns. The possibilities of reducing fuel consumption by increasing the thermal resistance of the lining of a rotary kiln are considered. The most energy-intensive zones are determined and the effect on the thermal efficiency of using additional thermal insulation in various energy zones in a rotary kiln is analyzed. Calculations and the results of a numerical experiment are presented. The most rational areas for the use of lining with additional thermal insulation are determined. It is found that with the integrated application of the proposed method, fuel consumption in a thermal unit can be reduced by 9 %. And an increase in the thermal resistance of the lining installed in high temperature zones will increase the energy efficiency of the thermal unit. A significant advantage of this method is the fact that an increase in kiln productivity does not require additional fuel consumption, an increase in temperature, or an increase in the enthalpy of combustion products.In the future, it is planned to study the mechanism for establishing a heat-insulating layer in the refractories of the lining, determining their optimal thermal efficiency and stress-strain state to eliminate the possibility of destruction. As well as determining the optimal structural form of the refractory and the cell with thermal insulation.

Life-cycle environmental assessment of energy-retrofit strategies on a campus scale

ABSTRACT The aim of this study is to determine the life-cycle environmental impacts associated with energy-retrofit strategies on an urban scale. A prototype campus model that includes deep retrofit clusters, moderate retrofit clusters, and baseline retrofit clusters is used as a case study. The retrofit strategies included major changes to the building envelope with additional insulation, replacement of exterior windows and doors, shading, primary mechanical system replacement, and lighting system replacement. The study aims to (1) compare the three levels of energy retrofit against the existing condition to determine potential reductions in environmental impact, (2) identify the life-cycle hotspots of the energy-retrofit strategies and possible mitigation methods, (3) calculate the payback time for each energy-retrofit level, and (4) demonstrate an example of how life-cycle assessment (LCA) could be used as a quantitative assessment method for energy retrofits done on a large scale. The life-cycle environmental impact is calculated for five categories. The results indicate that energy retrofits overall have a positive effect in terms of reducing life-cycle environmental impacts in all environmental categories except ozone-depletion potential. The deep energy retrofit has a much shorter payback time for its environmental-impact reduction than the other energy-retrofit levels.