Validation of data analysis routines for a thermal probe apparatus using numerical data sets

Most thermal properties of construction materials used in the analysis of building performance have been measured under laboratory conditions, using a guarded hot box or hot plate apparatus. As a consequence, these properties seldom reflect the impact of actual conditions (especially moisture content) on the values of conductivity and diffusivity. Hence there is a need to develop techniques that allow to take into account local conditions, and measure building material properties in situ. One option available is the use of a thermal probe. The thermal probe technique is based on creating a line source in a material sample, and measuring the temperature rise in the sample in reaction to heat being applied. Obviously the data analysis routines used to calculate thermal conductivity and thermal diffusivity based on the temperature rise observed are crucial to the success of the technique. Transient thermal simulation of a of a model representing a line source in an infinite material sample has been used to generate a set of numerical data sets to validate analysis routines in conjunction with an experimental thermal probe apparatus. Findings show that by careful application of these routines, a close agreement with simulation input values can be achieved, with errors of less than one percent. This validates the analysis routines and provides a deeper appreciation of the theoretical behaviour of a thermal probe

An assessment of the potential returns of energy certificates for the UK household sector

Purpose – This article seeks to investigate the interconnections between the expectations of the impact of energy certificates issued within the UK domestic building sector through the Energy Performance of Buildings Directive (EPBD) and the actual number and financial implications of the energy saving measures (ESMs) achieved. Design/methodology/approach – The methodology uses two previously published surveys and compares these with a third independent survey by the authors focusing upon the discrepancies between planned action and implemented action, introducing the term human factor element (hfe). Findings – The article concludes that annual carbon savings arising from implementation of the Energy Performance Certificate (EPC) may be as low as 73.4?ktC over the five year term of the Kyoto Protocol even though 44 per cent of energy saving measure costs of £200 million are recouped within the same time period and savings will continue for up to 40 years. Achieving annual savings of only 14.7?ktC by 2010, such a figure represents a mere 0.3 per cent of the annual domestic 4.8?MtC savings announced by the government in its 2006 Climate Change Programme. Practical implications – Since the principal determinant in the uptake of ESMs is initial cost, it is considered that the EPBD is likely to remain an under-performing instrument in the promotion of energy sufficiency until such time as other complementary provisions are introduced. Originality/value – Sheds light upon the likely financial impact upon energy efficiency in domestic buildings by energy certificates

Thermal probe technology for buildings: the transition from laboratory to field measurements

This article reports the results of an investigation into the transfer of thermal probe measurement technology from laboratory use to actual buildings in order to undertake the in situ determination of thermal material properties. The imperative for using in situ measurements is 1) the impact of moisture content on thermal properties, 2) the possible wide range of variation of properties across most materials used in construction, and 3) the lack of data for new and innovative materials. Thermal probe technology offers the prospect of taking building specific data, addressing these issues. Based on commercially available thermal probes a portable measurement kit and accompanying measurement procedure have been developed. Three case study buildings, each having different materials, have been studied to ascertain whether or not the technique can be transferred to relatively uncontrolled environments while remaining capable of achieving a precision that is similar to an ASTM standard that can be related to thermal conductivity measurements of building materials. The results show that this is indeed the case, and that the use of thermal probe technology may yield thermal properties that vary significantly from the laboratory values currently used in building thermal engineering calculations

Measured indoor temperatures, thermal comfort and overheating risk: Post-occupancy evaluation of low energy houses in the UK

There is growing concern in Western Europe that higher insulation and air tightness of residential buildings leads to increased overheating risk. This paper discusses temperature monitoring from identical houses in the Southwest of the UK that were built to low energy standards (Code for Sustainable Homes Level 5). The temperature data were analysed using both established static overheating criteria (CIBSE Guide A) and an adaptive thermal comfort standard (BSEN15251). The houses can be considered uncomfortably warm during summer and are at risk of overheating. The study suggests that occupant behaviour plays an important role in reducing or increasing internal temperatures

Building defect detection: External versus internal thermography

publisher: Elsevier articletitle: Building defect detection: External versus internal thermography journaltitle: Building and Environment articlelink: http://dx.doi.org/10.1016/j.buildenv.2016.06.011 content_type: article copyright: © 2016 Elsevier Ltd. All rights reserved

The squashed entanglement of the noiseless quantum Gaussian attenuator and amplifier

We determine the maximum squashed entanglement achievable between sender and receiver of the noiseless quantum Gaussian attenuators and amplifiers and we prove that it is achieved sending half of an infinitely squeezed two-mode vacuum state. The key ingredient of the proof is a lower bound to the squashed entanglement of the quantum Gaussian states obtained applying a two-mode squeezing operation to a quantum thermal Gaussian state tensored with the vacuum state. This is the first lower bound to the squashed entanglement of a quantum Gaussian state and opens the way to determine the squashed entanglement of all quantum Gaussian channels. Moreover, we determine the classical squashed entanglement of the quantum Gaussian states above and show that it is strictly larger than their squashed entanglement. This is the first time that the classical squashed entanglement of a mixed quantum Gaussian state is determined

The Thermal Performance Prospects of Courtyards in Cold Conditions

Aiming at developing more thermally comfortable and energy efficient buildings, some studies have been advocating using traditional architecture’s passive design strategies. Among the rarely investigated architectural elements to achieve this objective in cold climates is the courtyard space. This environmental element, in most cases, has been examined and suggested for hot conditions. However, some studies have shown indications of its potential environmental efficiency in cold conditions as well. In principle, courtyards enable having sheltered outdoor spaces to regulate indoor spaces’ interaction with the outdoor climate instead of having them outward oriented to directly face outdoor conditions. This research aims to determine whether this thermal performance of courtyards can be positive in cold conditions as it is in hot conditions, for instance, through protecting buildings from cold winds. To achieve this objective, the research conducted simulation experiments to determine the thermal conditions of 360 different courtyards and compared them with a typical modern urban outdoor space’s conditions. If the courtyard space offers a warmer environment than modern urban outdoor spaces, then it might lead to a wider positive impact on buildings’ thermal conditions and energy consumption. The used simulation tool to conduct the simulation experiments is Envi-met 4.2, which has been widely used and validated by previous simulation studies. The tested courtyard forms are of different geometric configurations to show a wide range of possible conditions in courtyards. The simulation was done for Baghdad, in which courtyards have been widely used for centuries. This city has a hot summer, but its winter temperature is between 0°C and 12°C. The Globe Temperature was used to determine peoples’ thermal sensation. Its value includes the impact of air velocity, radiation and air temperature, which makes it representing people’s actual thermal sensation properly. The results showed that courtyards offer higher Globe Temperature than modern urban spaces in cold conditions, mainly, through protecting buildings and occupants from winds. The air velocity inside courtyards can be one-tenth of air velocity in a modern urban outdoor space. The geometric properties of courtyards significantly affect courtyards’ thermal conditions. These results indicate that the courtyard space can be more thermally efficient than modern urban spaces even in cold climate conditions. However, its geometric properties need to be properly considered to have its highest possible thermal efficiency. Otherwise, the courtyard might lose its efficient thermal performance

An Adaptive Thermal Comfort Model for Residential Buildings ‎in Iraq

In Iraq, the temperature reaches around 0 °C in winter and 50 °C in summer. Aiming at providing thermal comfort for people, studies have been advocating developing innovative thermally responsive designs or adopting traditional architecture’s passive design strategies. However, to develop appropriate solutions for the country, it is critical to determine the thermal comfort limits to define the targeted thermal performance of buildings. This research worked on defining Iraqis’ thermal comfort limits in residential buildings for two reasons. First, they are the dominant building type in the country. Second, to inform the design of large housing developments Iraq is planning to have to satisfy large housing needs. Exploring previous literature in Iraq or regional countries shows that residential thermal comfort limits for people have not been defined properly. To achieve this aim, the research conducted thermal comfort survey in four Iraqi cities for a year. Nearly 4800 thermal comfort votes were recorded by 90 participants. The results show that the lower thermal comfort Globe temperature in winter is 17 °C and the highest acceptable Globe temperature in summer is 33 °C