External Surface Temperature Research Articles

Evaluation of blackbody-radiation frequency shift in strontium optical lattice clock

The frequency shift caused by blackbody radiation is one of the dominant corrections to the evaluation of the optical lattice clock. The frequency shift of blackbody radiation is closely related to the dynamic and static correction factor, ambient temperature and atomic polarizability. The blackbody radiation shift is mainly affected by ambient temperature. During the normal operation of the strontium atom optical lattice clock, the experimental environment and other heat sources around the vacuum cavity have complicated the environment around the vacuum cavity, resulting in the fact that the external surface temperature of the vacuum cavity does not truly reflect the temperature change of the vacuum cavity. For the strontium atomic optical clock experimental apparatus of the National Time Service Center, the uncertainty and correctionof the blackbody radiation frequency shift are evaluated by the theoretical analysis, measurement of the temperature of the vacuum cavity outer surface, and software simulation. Among them, the frequency shift of black body radiation caused by strontium atom furnace, sapphire heating window, room temperature radiation entering into the vacuum cavity through the window plate, and the thermal radiation at the atomic group caused by Zeeman reducer are analyzed. Five temperature measuring points are set on the external surface of the vacuum chamber, and the temperature changes on the external surface of the vacuum chamber are monitored in real time by using the calibrated platinum resistance temperature sensor while the system is running normally. We obtain the average temperature of the five temperature measuring points. The model of vacuum cavity is established by using the SolidWorks. The method of finite element analysis is used to simulate the variation of the temperature around atom samples. We also obtain the temperature distribution around the atomic groups in the vacuum cavity. The result shows that the temperature around atoms varies with the temperature of the vacuum cavity. When the temperature of the ambient temperature changes 0.72 K, the fluctuation of the temperature around the atoms is 0.34 K. Finally, the total correction of blackbody radiation of the system is evaluated to be –2.13(1) Hz, and the correction uncertainty is about 2.4 × 10<sup>–17</sup>.

Commingled black and white cows (Bos taurus; Angus and Charolais) in high-elevation rangeland are differentially parasitised by Haematobia irritans

Globally horn flies (Haematobia irritans) are one of the most economically damaging parasites of beef cattle. These obligate blood-feeding external parasites take blood meals from cattle leading to blood loss, annoyance avoidance behaviours, and reductions in animal performance. Development of chemical resistance by horn flies suggests that novel management strategies are needed. More in-depth understanding of parasitism relative to hide colour and temperature, especially in a changing climate, may enhance animal production. In peak parasitism periods of 2016 and 2017, we measured horn fly loads on commingled black Angus and white Charolais cows in a cold high-elevation rangeland in Wyoming, USA. We tested how breed, year, and interactions explained horn fly parasitism and economic thresholds. In 2016 we also measured ambient and external cow temperatures to further elucidate thermal ecology mechanisms explaining horn fly hide colour preferences. Mean annual horn fly infestations were always four times greater or more on black cows than white cattle both years, but not all cattle reached economic thresholds all years and the breed by year interaction was not significant. Difference in horn fly preference for black cattle over white cattle in our cold high-elevation environment may be explained by greater absolute and relative external surface temperatures of black hided cows. Host colour and thermal preferences of horn flies could be incorporated into integrated pest management strategies that only treat darker hided cattle and producers in cold high-elevation environments conduct real-time monitoring to determine if treatments are even needed on a year-by-year basis.

A theoretical study on a coupled effect of building envelope solar properties and thermal transmittance on the thermal response of an office cell

In recent decades, high level of urbanization, air pollution and climate change have caused a frequent occurrence of urban heat islands, resulting in thermal discomfort and increased energy use of buildings. As a response, a lot of attention has been paid to building envelope characteristics, with an increasing number of studies investigating building envelope solar properties as one of the important factors affecting thermal performance. However, different climate characteristics are the reason why solar properties may have different efficiency at various locations, also because in cold or temperate climates building envelope has to be more thermally insulated, namely having lower thermal transmittance. Therefore, within this study, building energy use and indoor thermal conditions were analysed for an office cell using different types of solar absorptivity (e.g. white, dark grey, collector or cool coating) and thermal transmittance, on either external wall or roof. The analysis was conducted for hot-arid and temperate climate locations. The results showed that solar absorptivity can have a significant effect on total energy use, especially in cases with higher envelope thermal transmittance. It also showed that the application of cool coatings is more reasonable if the external building envelope is not intensively thermally insulated (e.g. in hot-arid climate). In general, the optimal total energy use in both analysed climates was always achieved by implementing cool coatings. Furthermore, the results showed that white and cool coatings have comparable external (20–30 K above Tair in summer) and internal surface temperature responses, while dark grey coatings cause the surface to heat up significantly (external surface 60 K above Tair in summer).

Thermal behaviour of green façades in summer

Building greenery systems can represent a sustainable solution for new buildings design and for existing buildings retrofitting, in order to improve the thermal energy performance of buildings, to decrease building energy loads and to contrast the Urban Heat Island. Green façades can influence thermal properties of a building by means of different important mechanisms: the shading, the cooling, the insulating and the wind barrier effect. Moreover, green façades accomplish heating effect in the cold season and at nighttime. An experimental test was developed at small scale at the University of Bari (Italy) from 2014 to 2016 for testing two different green façades. The plant species chosen were Pandorea jasminoides variegated and Rhyncospermum jasminoides, two evergreen climbing plants. A third uncovered wall was used as control. The thermal behaviour of the plants was analysed during the 2016 summer season, by keeping in consideration the external surface temperature of the building and the temperature of the airgap behind the green vertical systems. The daylight temperatures observed on the plant-covered walls during representative days were lower than the respective temperatures of the uncovered wall up to 7.0°C. During nighttime, the temperatures behind the plants were higher than the respective temperatures of the control wall up to 2.2°C. The results shown in the present research allow delineating the behaviour of the two plant species during summer in the Mediterranean climate region.

Sweeping jet impingement heat transfer on a simulated turbine vane leading edge

With the development of additive manufacturing technology, it is now possible to design complex and integrated internal cooling architecture for a gas turbine engine. In search of a spatially uniform heat transfer at the leading edge of a turbine nozzle guide vane, a sweeping jet impingement cooling strategy was proposed. Experiments were conducted in a low-speed wind tunnel to investigate sweeping jet impingement cooling in a faired cylinder leading edge model at an engine-relevant Biot number (Bi). Sweeping jets were generated with additively manufactured fluidic oscillator and steady jets were produced by a cylindrical orifice (with length to diameter ratio of 1). Both sweeping and steady jets were studied at varying mass flow rates, jet-to-wall spacing (H/D), jet pitch (P/D), and freestream turbulence. The effect of varying aspect ratio (AR) of the sweeping jet geometries was also studied. The overall cooling effectiveness of each configuration was estimated using infrared thermography (IR) measurements of the external surface temperature of the leading edge model. The sweeping jet provided higher overall cooling effectiveness values compared to steady jet in specific configurations. The pressure drop across each jet was also measured for each geometry, and the sweeping jet shows comparable pressure drop to steady jet.

Calculation of the external surface temperature of a multi-layer wall considering solar radiation effects

ABSTRACT Infrared thermography has become a valuable tool for providing reliable information on the constructive components of the envelope of existing buildings and for checking if the thermal behaviour of a construction is consistent with the design parameters. However, infrared thermography has a limited capacity to offer quantitative accurate experimental results when the solar radiation incident on the facades is significant. The current study presents a methodology for theoretically calculating the external surface temperature of a multi-layer wall exposed to diurnal variations of the external environment temperature, which are caused by solar warming, hence validating a set of in situ measurements conducted using a thermographic camera over a time interval of interest. The measured external surface temperature is related to the theoretical equivalent sol-air temperature and the external and internal air temperatures by the numerical solution of the heat equation that is used to estimate the heat flux through a non-homogeneous medium. In addition, the numerical results are successfully compared with those obtained using the analytical standard admittance method. Thus, the instantaneous measurements of the external surface temperature can be generalised to calculate the heat flux into the building while considering the solar radiation effects during extended periods of time.

Impact of post-rainfall evaporation from porous roof tiles on building cooling load in subtropical China

Rainfall occurs frequently in subtropical regions of China, with the subsequent water evaporation from building roofs impacting the thermal performance and the energy consumption of buildings. We proposed a novel simulation method using actual meteorological data to evaluate this impact. New features were developed in EnergyPlus to enable the simulation: (1) an evaporation latent heat flux source term was added to the heat balance equation of the external surface and (2) algorithms for the evaporative cooling module (ECM) were developed and implemented into EnergyPlus. The ECM experimental results showed good agreement with the simulated results. The ECM was used to assess the impact of evaporation from porous roof tiles on the cooling load of a one-floor building in subtropical China. The results show that the evaporation process decreased the maximal values of the external and internal roof surface temperatures by up to 6.4 °C and 3.2 °C, respectively, while the lower internal surface temperature decreased the room accumulated cooling load by up to 14.8% during the hot summer period. The enhanced EnergyPlus capability can be used to evaluate the evaporative cooling performance of roofs with water-storage mediums, as well as to quantify their impact on building cooling loads.

Study of dual-phase drive synchronization method and temperature measurement algorithm for measuring external surface temperatures of ethylene cracking furnace tubes

Currently, the manual method using hand-held infrared temperature measurement instruments for measuring temperatures on the external surfaces of ethylene cracking furnace tubes is highly subjective and is affected by a number of prominent issues, such as the high temperature working environments, which leads to low efficiency and poor measurement accuracy. Hence, an automatic temperature measurement system based on infrared light is designed and realized. In the system, a dual-phase drive synchronization method is proposed to rotate the thermodetector during horizontal movements, thus realizing automatic batch temperature measurements of the furnace tubes. Moreover, a temperature processing algorithm is developed to automatically identify furnace wall and tube surface temperatures, filter out abnormal temperatures and select only high-quality temperature measurements prior to calculating the final result. Real temperature measurement experiments demonstrated that the dual-phase drive temperature measurement system and temperature processing method are effective and efficient. Compared with the traditional manual way, temperatures obtained using the proposed system are more stable and accurate.

How to enhance thermal energy storage effect of PCM in roofs with varying solar reflectance: Experimental and numerical assessment of a new roof system for passive cooling in different climate conditions

In last decades, the effectiveness of thermal energy storage (TES) systems for energy efficiency has been widely studied when integrated to building envelope, often as latent strategy by means of Phase Change Materials (PCM). In this view, the present study investigates the dynamic thermal performance of an innovative cool polyurethane-based membrane with PCMs inclusion for roofing applications. Such membranes were developed in previous works when the new composite material was characterized in terms of thermal-optical and morphological properties, when integrating PCMs with transition point at 25 °C and 55 °C. In this work, such materials is finally implemented into a roof multilayer structure, and additional experimental tests are carried out in a dedicated environmental simulation chamber, where the thermal performance of the novel lightweight roof stratigraphy is investigated. To this aim, two types of membranes for roofing applications, i.e. the innovative proposed cool membrane and a more traditional dark bitumen membrane, are considered. These two roof configurations are tested with and without the integration of PCMs, with varying the melting temperature range, in two different climate boundary conditions, i.e. Mediterranean climate of Rome, Italy, and Hot desert climate of Abu Dhabi, UAE. Moreover, numerical analysis of the roof thermal behavior is carried out through transient heat transfer calculation. Therefore, the two roof configurations are simulated and compared, in the same selected climate conditions and with varying PCMs.Findings of coupled experimental tests and numerical analysis show that the combination of cool membrane and PCMs with suitable melting temperature range allows to significantly reduce the roof surface temperatures and, therefore, the heat flux through the roof. In detail, results of numerical analysis demonstrate how in Rome the integration of PCMs with melting point around 25 °C and 45 °C in the cool and the dark roof membrane, respectively, has a great effect in reducing the external roof surface temperature. On the contrary, in Abu Dhabi, the configuration allowing the higher inward heat flux reduction is represented by the integration of PCMs with melting point around 35 °C and 55 °C in the cool and dark membrane, respectively. On the other hand, experimental tests show how the inclusion of a PCM layer with melting point around 25 °C and 31 °C under the cool and dark coating membrane, respectively, allows the best thermal performance in both climate conditions. Therefore, this work showed the promising effectiveness of PCMs inclusion to improve the thermal performance of waterproof membranes for roofing applications. However, as demonstrated, the selection of the proper PCM melting temperature should be operated by taking into account not only the climate conditions, but especially the roofing medium and the position in the roof stratigraphy where thermal energy storage materials are integrated. In fact, roof coating thermal behavior is largely influenced by its thermal-optical properties, e.g. solar reflectance and thermal emittance.

Boundary Conditions Accuracy Effect on the Numerical Simulations of the Thermal Performance of Building Elements

Numerical simulation is widely used in the field of computational building physics for the definition of the thermal performance of building elements. An integral component of numerical simulation using finite elements is the boundary conditions, which, in the case of simulating the thermal performance of a building element, are usually expressed in terms of the external surface temperature as a function of time. The purpose of this study is to examine the effect of the accuracy of the boundary conditions on the thermal performance simulation of building elements. The assumption that the temperature versus time is a sinusoidal function, applied in standard methods, is comparatively assessed with the actual function for diverse climatic conditions using finite elements simulation. The findings of the analysis indicate that the sinusoidal function fails to accurately simulate real boundary conditions. The originality of this study lies within the adoption of a signal reconstruction algorithm, which follows a novel approach by reconstructing the actual temperature versus time signal for the simulation of the actual boundary conditions.

Impact of passive cooling techniques on the thermal behavior of residential buildings in hot and arid regions -An experimental study-

The thermal performance of the is one of the most important factors for a comfortable environment. As 50% of the thermal loads received by a building come from the roof, this research seeks to find the roofing system that opposes the transmission of heat during the hottest days and promotes indoor thermal comfort. In this regard, this paper presents an experimental study carried out on four (04) testing cells constructed on a reduced scale and submitted to climatic external conditions. Three (03) cells were used to test passive cooling strategies through the roof, namely: the roof, ventilated and a with inverted earth pots. The fourth cell that served as cell-reference, for its part, a conventional roof. The experimentation concerned the types of roofs most used in residential buildings in Biskra, Algeria. The measurements process was effectuated in an exposed field during the month of July, prevailing the metrological data of the hot and arid climate. The obtained results show that the use of the cool-roof technique makes it possible to record the lowest internal temperatures in comparison with the other systems. Thus, the reflective coating technique is capable of reducing the internal temperature from 3.33 °C to 4.80 °C, also the internal and external surface temperature of the roofs from 5.31 °C to 10.18 °C, respectively. These experimental results confirm the effectiveness of the cool roof technique as an innovative and efficient solution that contributes to the achievement of the comfort conditions in a hot and arid climate by eliminating heat gains through the roof.

Impact of passive cooling techniques on the thermal behavior of residential buildings in hot and arid regions -An experimental study-

The thermal performance of the roof is one of the most important factors for a comfortable environment. As 50% of the thermal loads received by a building come from the roof, this research seeks to find the roofing system that opposes the transmission of heat during the hottest days and promotes indoor thermal comfort. In this regard, this paper presents an experimental study carried out on four (04) testing cells constructed on a reduced scale and submitted to climatic external conditions. Three (03) cells were used to test passive cooling strategies through the roof, namely: the cool roof, ventilated roof and a roof with inverted earth pots. The fourth cell that served as cell-reference, for its part, a conventional roof. The experimentation concerned the types of roofs most used in residential buildings in Biskra, Algeria. The measurements process was effectuated in an exposed field during the month of July, prevailing the metrological data of the hot and arid climate. The obtained results show that the use of the cool-roof technique makes it possible to record the lowest internal temperatures in comparison with the other systems. Thus, the reflective coating technique is capable of reducing the internal temperature from 3.33 °C to 4.80 °C, also the internal and external surface temperature of the roofs from 5.31 °C to 10.18 °C, respectively. These experimental results confirm the effectiveness of the "cool roof" technique as an innovative and efficient solution that contributes to the achievement of the comfort conditions in a hot and arid climate by eliminating heat gains through the roof.

The impact of urban green infrastructure as a sustainable approach towards tropical micro-climatic changes and human thermal comfort

Green infrastructures such as living walls are technological solutions to replace the declined greenery at urbanized environment and also reliable applications for thermal regulation in buildings through insulation effect and escalates the energy use efficiency. Thermal comfort and local climate are spatiotemporally variable. The existing research gap should be addressed by evaluating the performance of vertical green walls in tropical condition. In this study, thermal performance, relative humidity (RH) and CO2 concentration were quantified for basic three types of green infrastructures; such as (T1) living walls, (T2) indirect green façades and (T3) direct green façades located in Colombo metropolitan in Sri Lanka. An in-situ experimental study was conducted considering temperatures at 1 m and 0.1 m distance in front of the green walls, inside the foliage, air gap and external wall surface comparatively to adjacent bare wall control. Three case studies per green infrastructure within Colombo metropolitan area were purposively selected. Simultaneously, RH and CO2 concentration at 0.1 m in front of the green and bare walls were measured for the performance quantification. The internal thermal comfort simulation and occupants’ satisfaction questionnaire survey was executed to assess the green infrastructure performances. The study revealed that vertical greenery systems were highly effective on external wall surface temperature reductions at 1100 h–1500 h time zones. T1 and T2 accounted for superior temperature reduction in the range of 1.61 °C–1.72 °C through the façade relative to the distance than T3. Maximum temperature reduction compared to the bare wall control was obtained for the T1 (0.28 °C–8.0 °C) followed by T2 (1.34 °C–7.86 °C) and T3 (1.34 °C–6.64 °C). Averaged RH increment (1.6%–1.81%) and CO2 reduction (0.63%) occurred near green walls at day time compared to control. An average 28 °C simulated indoor temperature circumstantiate the indoor thermal comfort. 58% and 89.5% occupants’ were satisfied with thermal and visual comfort respectively, thus emphasizing façade greening as a sustainable approach on micro climatic changes and human thermal comfort.

Thermal behaviour of a building in its environment: Modelling, experimentation, and comparison

A building influences its surrounding external environment, and its indoor environment is usually sensitive to its surroundings. In order to obtain a more accurate prediction of the indoor thermal behaviour of a building or a building stock, it is necessary to consider the interactions between the indoor and outdoor thermal environments.The modelling approach presented in this paper is based on a building energy model and the urban modelling tool SOLENE-Microclimat. A sensitivity analysis is undertaken to highlight the parameters which influence the performance of the building model. Then, the thermal indoor behaviour of a building is compared to in situ experimental measurements and the outdoor thermal environment is evaluated in terms of external surface temperatures. The model's accuracy and behaviour is evaluated and a crossover approach with the sensitivity analysis results is proposed. The model obtains a good level of performance for almost all variables, unless some external surface temperatures intervals.

Critical analysis of the condensation of water vapor at external surface of the duct

In this paper, the effects of contraction of the insulation of the air duct of heating, ventilation, and air conditioning (HVAC) system is investigated. The compression of the insulation contracts it at joint, turn and other points of the duct. The energy loss and the condensation resulted from this contraction are also estimated. A mathematical model is developed to simulate the effects of this contraction on the heat gain, supply air temperature and external surface temperature of the duct. The simulation uses preliminary data obtained from an HVAC system installed in a pharmaceutical company while varying the operating conditions. The results reveal that insulation thickness should be kept greater than 30 mm and the volume flow rate of the selected air distribution system should be lower than 1.4m3/s to subside condensation on the external surface of the duct. Additionally, the optimum insulation thickness was determined by considering natural gas as an energy source and fiberglass as an insulation material. The optimum insulation thickness determined for different duct sizes varies from 28 to 45 mm, which is greater than the critical insulation thickness. Therefore, the chances of condensation on the external surface of the duct could be avoided at an optimum insulation thickness. Moreover, the effect of pressure loss coefficient of the duct fitting of air distribution system is estimated. The electricity consumption in air handling unit (AHU) decreases from 2.1 to 1.5 kW by decreasing the pressure loss coefficient from 1.5 to 0.5.

Experimental Research on the Effect of Materials of One Turn Swiss Roll Combustor on Its Thermal Performance as a Heat Generating Device

Looking at the present need of small scale power generation to run devices like small thrusters, cellular phones, laptops etc. attempts were made to develop small scale power generating devices. But issues increases with downsizing of the small scale power generators. Present work mainly focuses on the experimental investigations carried out on different materials (i.e. Aluminum, copper, stainless steel and brass) which were manufactured as one turn Swiss roll combustor. Studies were carried out on the Swiss roll combustor for fixed depth of 20mm. Reactants channel dimension and Products channel dimensions were 2mm and 3mm respectively. During the experiments conducted parameters varied were equivalence ratio and materials of the combustor. Parameters measured during the experiments were flame stability limits, external surface temperatures, combustion space/room temperatures. External surface heat loss to atmosphere was calculated for different values of equivalence ratio. Flame was observed stable successfully during all the experiments conducted. Heat transferred on all the external surfaces from the combustion space can be used as heat input to thermal electric devices. Higher heat content values were observed for SS material and lower values for Br material. Equivalence ratio equal to 1.068 was found to be the best at which maximum temperatures and heat content observed for all the materials. Maximum total heat content of 39.21W was observed for SS material. Lean limit temperatures were observed to be higher compared to rich limit temperatures.

Finite element analysis of a thermally insulated infrared radiant emitter

The purpose of this work is to analyze the efficiency of the technical solution that is based on thermal insulation of the infrared radiant burner outer surface and to identify of the characteristics of combustion and heat and mass exchange processes. Calculation of the heat balance is performed for thermal capacities of 5, 10, 15, 20, 30, 40 kW and proceeding from the main goal that was to generate directed local heating of workplaces and production areas. We used Ansys Multiphysics software and Fluent CFD solver to implement finite element analysis. Calculation of the thermal insulation layer thickness for a given external surface temperature was additionally performed. The technical solutions offered provides an optimal thermal regime in the whole building and enable us to increase the efficiency of the high temperature infrared radiant emitter to 2-17% and a consequence of the system as a whole.

Attenuation of Temperature Fluctuations on an External Surface of the Wall by a Phase Change Material-Activated Layer

Periodical changes of temperature on an external surface of building envelope, e.g., thermal stress or excessive heat gains, is often an undesirable phenomenon. The idea proposed and described in the following paper is to stabilize the external surface temperature in a period of significant heat gains by the originally developed, novel composite modified by phase change material (PCM) and applied as an external, thin finishing plaster layer. The PCM composite is made from porous, granulated perlite soaked with paraffin wax (Tm = 25 °C) and macro-encapsulated by synthetic resin. The effect of temperature attenuation was estimated for two designated periods of time—the heat gains season (HGS) and the heat losses season (HLS). The attenuation coefficient (AC) was proposed as evaluation parameter of isothermal storage of heat gains determining the reduction of temperature fluctuations. The maximum registered temperature of an external surface for a standard insulation layer was around 20 K higher than for the case modified by PCM. The calculated values of AC were relatively constant during HGS and around two times lower for PCM case. The obtained results confirmed that the proposed modification of an external partition by equipped with additional PCM layer can be effectively used to minimize temperature variations and heat flux in the heat gains season.

Impact of plants occultation on energy balance: Experimental study

This paper presents the results of the validation of an experimental method for studying the thermal benefits of green façades. The main aim is to evaluate the impact of plants occultation on energy performance of a vertical wall in the temperate climate of the city of Lille in northern France. An experimental platform consisting of three identical prototypes (three boxes as thermal labs) has been designed and instrumented. Each prototype has been highly insulated from each face except from the vertical southern wall which was realized with a poor thermal conductivity material. The following measurements were taken: ambient temperature (outside and inside thermal labs), external and internal surface temperatures of southern walls, heat fluxes transferred through south verticals walls (reference and vegetalized walls), solar incident radiation and wind velocity variation under instantaneous real climatic conditions. This enabled the analysis of the variation of energy balance according to the presence or not of a shading effect on the south vertical walls as well as their coverage rate. Several tests were performed on the three experimental thermal labs by imposing a leaf coverage rate which differs during each measurement. The results have shown that masking reduces the outside temperature and enhances the interior thermal comfort especially during summer.

Parametric study of condensation at heating, ventilation, and air-conditioning duct's external surface

The compression of insulation causes around a heating, ventilation, and air-conditioning duct usually resulted in dew formation around the outer surfaces because of low temperature, which causes significant energy and financial losses. The parameters such as supply air flow rate, supply air temperature, ambient air speed, and the convective heat transfer coefficient (ho) plays significant role in dew formation. In this paper, the parametric study is performed to investigate the effects of these parameters on the external surface temperature of the duct to avoid condensation. A mathematical model is developed to quantify these effects using preliminary data obtained from the heating, ventilation, and air-conditioning system of a pharmaceutical company. The results reveal that external surface temperature increases with an increase in insulation thickness and supply air temperature, whereas it decreases with higher supply air flow rate. It is estimated that the minimum insulation thickness at joint and bend should be maintained between 15–55 and 15–35 mm, respectively, with a variation in ho between 6 and 22 W/m2K to avoid condensation. Additionally, it is estimated that air flow rate should be greater than 1.4 m3/s at 10 W/m2 K and 2.2 m3/s at 22 W/m2 K. Similarly, the ambient air speed should be greater than 2.8 m/s at 6 W/m2 K, respectively. Practical application: Building services engineers have a paucity of information on the effects of the compression of heating, ventilation, and air-conditioning duct thermal insulation. It can cause condensation that will adversely affect the insulation material, thereby increasing the maintenance cost as well increasing the heat loss from the duct so affecting the conditions of supply air. Proper insulation thickness and operating parameters are important for building owners and operators to control ongoing expenses of buildings. This paper seeks to quantify the effect of insulation compression to improve understanding so that this important area may be properly considered by the building services engineer.