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Reducing energy consumption and Greenhouse Gas (GHG) emissions is an essential part of the clean growth and climate change framework recently developed by the Canadian government, which emphasizes the importance of energy-efficient building constructions. In this paper, the effects of thermal mass and placement of the thermally massive layer within wall assemblies on the transient thermal performance of walls and energy performance of a case study office building were studied. Three climate conditions representative of the heating-dominated, temperate, and cooling-dominated climates were considered. As for the assessment of energy demands, two cases for the indoor air temperature were taken into account: (i) indoor temperature was maintained at 20°C throughout the year, and (ii) during summertime, there was a set-point of 24°C and a setback of 35°C during the rest of the day while during wintertime, the set-point and setback values were 22°C and 18°C, respectively. The cases were compared according to the resulting decrement factor, the time required to reach quasi-steady state conditions, amplitudes of changes of heat fluxes and indoor surface temperatures, and the energy demands. The results showed that, for the cases studied, the wall, for which the thermally massive layer is not directly exposed to the indoor and outdoor climate conditions, resulted in the lowest decrement factor, the minimum amplitude of changes of heat fluxes and indoor surface temperatures, and maximum time required to reach quasi steady-state conditions. As for the energy performance, on the other hand, the wall, for which the thermally massive layer is exposed to the interior and exterior climate conditions, performed best amongst the cases investigated. [ABSTRACT FROM AUTHOR]

Thermal performance of building enclosure is typically based on laboratory tests performed on dry materials without consideration of air and moisture movement through the assembly. To address the field performance of the assembly, however, one must combine measurements and hygrothermal modeling. Hygrothermal models are necessary to include effects of climate and in particular the effects of moisture movement on thermal performance. Full-scale testing is necessary to relate findings of the models to actual construction details. The first paper in this series (Bomberg and Thorsell, 2008) introduced a test program that starting with benchmarking of the R-value of the tested wall in standard conditions, examined the effects of air flow on its thermal performance. This test program does not use the average R-values of the wall as it is in the ASTM testing, but measures local thermal resistance in selected places and calculates the average R-values. The second paper in this series (Thorsell and Bomberg, 2008) applied this integrated testing and modeling approach to selected wood framed residential walls, identifying the magnitude of air flow effects on steady-state thermal resistance, as well as demonstrating that the thermal performance of the top of the wall differs from that at the bottom. It also showed a systematic and time dependent shift in thermal performance caused by moisture movement. In this, third paper in the series, we present measurements performed on metal frame walls that introduce additional sources of uncertainty in the experimental results. We end with a discussion on the need of improvements to testing procedures for evaluation of energy performance of building enclosures. [ABSTRACT FROM PUBLISHER]

Increasing the thermal resistance of masonry wall systems is one of the effective ways to reduce energy consumption in the operation of masonry buildings. This increase is also demanded by newer, more stringent energy codes. However, the effective thermal resistance (R -value) of masonry walls is affected by many factors, such as thermal bridging, which occurs in places where highly conductive structural components penetrate insulating materials. Thermal bridging is common when connecting masonry veneers to structural backup walls. Furthermore, quick and precise methods for estimating the R -value are needed for thermal design improvements and code-compliance calculations. This study presents a comprehensive literature review on key factors that influence the overall thermal performance of masonry walls, methods to effectively estimate and measure R -values, and improvements in thermal design. In addition to identifying the main technical and practical challenges and the corresponding progress made on each front, key design considerations, such as code compliance, material properties, insulation types, and location, as well as special ties and shelf angles types, are also discussed. This study summarizes critical information and recommendations that will help improve the thermal design of masonry walls, hence reducing the energy consumption of buildings. [ABSTRACT FROM AUTHOR]

The measurements for the short-wave solar reflectivity of a Reflective Coating Material (RCM) with various cleaning operations that were obtained in a previous study were used in this study to conduct numerical simulations in order to assess the moisture and energy performance of cool and black roofs when they were subjected to the weather conditions of Saudi Eastern Province and Kuwait City. The results of the numerical simulations showed that black roofs always work with less moisture than cool roofs. Because the highest relative humidity in the different components of the black and cool roofs was well below 80%, there was no risk of condensation and mold growth in these roofs. For both weather conditions of Saudi Eastern Province and Kuwait City, the results showed that installing cool roofs have resulted in increasing the heating energy loads in relation to black roofs. Conversely, the results showed that the decrease in the cooling energy loads due to installing cool roofs were typically much greater than the increase in the heating energy loads. As such, cool roofs have resulted in net energy savings in relation to black roofs. Replacing black roof by cool roof in Saudi climate, the results showed that the annual energy savings in the total energy load was 25% and 34% as a result of installing cool roof with RCM at no cleaning and weekly homemade cleaning, respectively. Additionally, replacing black roof by cool roof in Kuwaiti climate, the results showed that the annual energy savings in the total energy load was 23% and 31% a result of installing cool roof with RCM at no cleaning and weekly homemade cleaning, respectively. [ABSTRACT FROM AUTHOR]

In order to get more comprehensive operation performance on indoor environment quality (IEQ) and energy consumption, a long-time measurement and a field occupants' satisfaction survey on IEQ performance of the first three-star-operation-certified green office building in Ningbo city of China have been conducted, and environmental energy efficiency (EEE) also has been analyzed. Moreover, IEQ and energy consumption of the green case office building are compared with other green office example buildings of the same climate zone in other literatures. The results show that the actual indoor thermal environment of the green case office building isn't quite achieving the design goals with the Chinese standard of thermal comfort level II (GB 50736). Although indoor air quality of CO2 concentration and visual environment are consistent with the design goals, the indoor relative humidity doesn't reach the design goal in most of the year. The questionnaire survey results illustrate that the green case building has a high occupants' satisfaction on IEQ. The comparison results show that there is no obvious difference in indoor temperature and visual environment between the green case building and the green office example buildings in other studies. The results of occupant's satisfaction and CO2 concentration of the green case building are better than in other studies. However, the indoor relative humidity of the green case building in every season is much higher than in other researches. Energy use intensity (EUI) of the green case building is about 56.5 kWh/m2·a, which is much lower than the constraint value of the Chinese standard. The actual performance of the green case building is also evaluated by the indicator of EEE. The results of this article can provide useful reference for green building operational performance promotion and feedback for design phase optimization. [ABSTRACT FROM AUTHOR]

The theme of the energy requalification of historic buildings is addressed considering the Palaeontology Museum of Naples (Southern Italy). It is assessed whether, through non-invasive methods and without intervening on the building envelope, it is possible to obtain internal hygrothermal parameters suitable to allow both occupants' thermal comfort and satisfactory conservation conditions for the archaeological finds. In addition, a relevant reduction of energy requirements and CO2 equivalent emissions is required. Dynamic energy simulations are conducted regarding both the current configuration and the various possible modifications concerning the air conditioning system; the model is calibrated by comparison with real energy consumption data. The electric and primary energy are compared for the various cases. Furthermore, the internal hygrothermal conditions for occupants' thermal comfort and for conservation of the archaeological finds are analysed. Finally, the possibility of inserting a suitable and minimally invasive photovoltaic system is evaluated and an almost 'Double Plus-Zero Energy Building' is obtained. [ABSTRACT FROM AUTHOR]

The author talks about the progress of building physics. He notes that such small niche of applied science has evolved to become one of the leading fields in building in the 21st century in which aspects such as indoor air quality, energy efficiency of buildings and other fields of engineering activities tend to be a subset of simultaneous heat, air and moisture transfer. He mentions that the U.S. and Canada prefer the term building science over building physics as the latter is said to be more practical and more performance-oriented.

The previous part of this article starts 100 years ago, at the time of the humble beginnings of building science, and brings us to the current stage of the net zero energy buildings (NZEB). We see how, over the years, knowledge from the observed failures of buildings has accumulated to become the basis for current building science. The strong interactions between energy efficiency, moisture management, and indoor environment and the need for their simultaneous analysis led to the concept of environmental assessment. More than 40 years of experience with passive houses (the first 10 were built in Canada in 1977) in process that would collect those developments into the mainstream of NZEB technology permits extrapolation to the future. As the first priority, we see a need for a fundamental change in the approach to NZEB—instead of improving the separate pieces of the puzzle before assembling them, we need first to establish the conceptual design of the whole system. Only after determination of the basic requirements for each subsystem and each assembly may materials that would fulfill the specific requirements of this assembly be selected. In this design process, the actual climate and socio-economic conditions (including construction cost) vary, so we must deal with a set of design principles rather than a description of a specific construction technology. A guiding set of considerations is presented below to establish a system of environmental quality management (EQM). [ABSTRACT FROM AUTHOR]

In the first part of this series, we discussed that the building structure, energy efficiency, indoor environmental quality, and moisture management all need to be considered simultaneously to ensure durability of materials and control cost of near-zero energy buildings. These factors must be addressed through contributions of the whole design team. It is also evident that building physics must take an active role in development of near-zero energy buildings. The need to ensure good indoor environment and durability of materials and limit the cost of buildings led to integrated design process that now is typical in Canada for design of low-energy buildings. Furthermore, interactions between energy efficiency, quality of indoor environment and moisture management led us to introduce a concept of “environmental control.” In the meantime, we made an unexpected observation—Vancouver dwellings in 2002 use the same amount of energy as 1920 uninsulated masonry buildings erected in the same location. We concluded that despite having advanced technology, our lack of vision prevents us from an effective use of this technology. With the quest for sustainable buildings, we should learn more from termites, who appear to master the art of hygrothermal control better than humans as they are capable of maintaining highly stable interior comfort zone without heating, ventilating, and air-conditioning equipment. Nevertheless, whatever progress is achieved in new low-energy buildings, it is lost when rehabilitating existing buildings because there an owner will typically do one step at a time. If the financial constraints do not allow for more, this first step should be an integrated action that includes a combination of insulation and heating systems. [ABSTRACT FROM AUTHOR]

A model has been designed to dynamically analyze and optimize energy consumption in building as integrated in Iran and other countries. This model can cover all characteristics and potentials of different types of building energy models and improve their weaknesses. The first part of this article discusses the capabilities and equations dominating the designed model. It also compares the strengths and weaknesses of the model with those of the existing models considering their historical literature. In this article, the application of the designed model for a XYZ case study building located at north of Tehran has been evaluated. Aiming at verification of the model, the outcomes were compared with the actual data for a 10-story high rise in 2011, and accuracy of the data was then verified by statistical standards. Finally, the typical optimized integrated multienergy systems model for the residential high rise was adopted after fulfilling the energy optimization phases. Using this model, with the initial investment cost of US$751,867 allotted to optimization, payback period of 6.1 years, and adjusted internal rate of return equal to 20.6%, energy consumption saving of nearly 60% can be achieved during 2011. [ABSTRACT FROM AUTHOR]

Air leakage through the building envelope into the building interiors has a considerable impact on the energy loads and consequently energy demand and energy costs of buildings. This phenomenon known as infiltration happens through various openings and venues in the building envelope varying from large openings such as doors and windows to minute cracks and crevices. In addition to impacting building energy loads, infiltration impacts indoor air quality and can result in moisture accumulation problems in the building envelope. A generalized review of infiltration that includes evaluation techniques and models, quantification, and interaction with other heat transfer phenomena is presented in this article. [ABSTRACT FROM AUTHOR]

Indoor air quality, occupant’s comfort, durability of building parts, and energy consumption are highly related to the variations in indoor relative humidity. Since interior finishes and objects assist in dampening the peaks in relative humidity, the knowledge of the moisture buffer potential of room enclosures is necessary to include its effect in whole-building simulations. In this article, a method for the in situ determination of the moisture buffer potential of room enclosures is presented. During a period of some days, a humidifier is placed in a room and a moisture production scheme is implemented. Based on the measured RH-increase and decrease during loading and unloading steps, the ventilation rate and moisture buffer potential of the room are determined inversely by solving the moisture balance of the room using the effective capacitance and effective moisture penetration depth models. The methodology is validated by well controlled experiments in a large climatic chamber with known hygric inertia, and afterwards applied to real room enclosures. Main advantage of the proposed method is that a simple and fast experiment allows obtaining a comprehensive characterization of the hygric inertia of the whole building enclosure — including all interior finishes and multidimensional interior objects such as furniture, carpets, drapes, books, etc. [ABSTRACT FROM PUBLISHER]

In the building science area, mathematical models are developed to provide better indoor thermal comfort with lower energy consumption. Although the fact moisture and air transfer can strongly affect the temperature distribution within constructions, whole-building simulation codes do not take into account the convective air transport in porous materials. In this way, this article presents a heat, air, and moisture (HAM) transfer model based on driving potentials of temperature, air pressure, and water vapor pressure gradients for consolidated porous material in both pendular and funicular states. The solution of the set of governing equations has been simultaneously obtained using the MTDMA (MultiTriDiagonal-Matrix Algorithm) for the three potentials. To conclude, results are presented showing the impact of convective terms on the HAM transfer through a two-layer porous building envelope. [ABSTRACT FROM AUTHOR]

It is often forgotten that the building sector consumes more energy than the transportation sector. To meet expectations and needs of our society, one must seek significant improvements in the efficient use of energy for this purpose. In many instances our normal approach based on conventional testing methods is not comprehensive enough. For instance, the thermal performance of a wall is defined by tests performed on dry materials, without considering the air and moisture movements. The energy performance of materials and building assemblies is affected by moisture and air flows. The authors believe that a more precise means of evaluation of the thermal performance of assemblies must be used to guide us in developing construction practices that lead to better performance. This should include consideration of air and moisture transfer under field conditions. The previous part of this study describes the limitations of conventional thermal resistance testing using calibrated hot boxes and explains that the effect of climate on thermal performance must also involve use of computer models that are capable of simultaneous calculations of heat, air, and moisture (HAM) transfer. In this study, the integrated testing and modeling methodology proposed is applied to a few selected residential walls to highlight the magnitude of air flow effects compared with steady-state thermal resistance without air flows. Effectively, to characterize energy performance of the building enclosure, one must use an integrated methodology that uses both testing and modeling. The study represents a first step in this direction. [ABSTRACT FROM AUTHOR]