Building Services Engineering Research & Technology

This is a paper updating the paper I wrote on this topic for BSERT in issue 1 volume 1 in 1980. The original paper set out the causes of failure in building design as being due to various issues such as an inadequate brief, lack of data, poor communication, inadequate analysis or synthesis, quirks of human behaviour which could all contribute. Systematic appraisal – now referred to as post-occupancy evaluation – of buildings in use provides feedback which helps us to understand why theory and practice do not always agree and also gives evidence for improved building economics. It concluded that we have to involve users more in the design of buildings, and for the next generations, we need a much broader based education of building designers. This paper continues the theme by considering the latest methods of measurement and assessment which provide feedback data for sustainability but focusing more on health and wellbeing rating assessments.

Practical application: Our professions need more interaction across sectors and to foster a transdisciplinary approach. This means more communication with other professional kinsmen from the health and wellbeing sectors in order to make valuable interventions in the building design process. This paper updates the 1980 paper from the first edition of BSER&T that sets out the causes of failure in building design as being due to various issues such as an inadequate brief, lack of data, poor communication, inadequate analysis or synthesis, quirks of human behaviour which could all contribute. The paper determines that the need for feedback in order to improve building performance and provide data to develop existing guidelines, codes and standards is as valid now as it was in 1980 but the way we do this has changed.

This paper discusses the characterisation of micro-channel absorber plates for compact flat plate solar thermal collectors, which are suitable for building integration. Experimental and computational studies were carried out at typical operating conditions for flat plate solar collectors. Three-dimensional numerical analysis using commercial CFD package, ANSYS CFX, showed that heat transfer occurred on only three surfaces of the channel and there was a peripheral variation of the heat flux density. It was also observed that axial thermal conduction could modify the surface boundary at the inlet and outlet; however, the middle section of the channel could be approximated as a rectangular channel with three walls transferring heat under an H1 boundary condition. Experimental studies were used to estimate the standard parameters for predicting performance of the flat plate collectors, which indicated promising performance results. The collector flow factor F″ and the heat removal factor could be improved by increasing the collector capacitance rate; this can be achieved by increasing the mass flow rate per collector area m · / A c as well as reducing the overall heat loss, U_L. This analysis is important for optimising design and operating parameters, especially to minimise temperature gradient in the transverse and longitudinal directions.

Practical application : The proposed compact micro-channel absorber plate has the potential to make flat plate collectors more efficient, cheaper and aesthetically attractive in building integration. It could therefore promote the uptake of solar thermal collectors in buildings. The analysis presented in this study would be beneficial for optimising the design and operating parameters of building integrated solar thermal collectors with micro-channels.

The accurate prediction of building indoor overheating risk is critical in order to mitigate its possible consequences on occupant health and wellbeing. The Chartered Institution of Building Services Engineers issued Technical Memorandum 59 (TM59) with the aim of achieving consistency in the modelling processes followed for the prediction of overheating risk in new dwellings. However, as each tool’s prediction may depend on its inherent assumptions, an inter-model comparison procedure was used to assess whether the choice of building performance simulation tool influences the overheating assessment. The predictions of two popular tools, IES VE and EnergyPlus, were compared for nine variations of a naturally ventilated, purpose built, London flat archetype, modelled under the default algorithm options. EnergyPlus predicted a high overheating risk according to TM59 criteria in seven out of the nine model variants, contrary to the low risk of all the IES VE variants. Analysis of heat transfer processes revealed that wind-driven ventilation and surface convection algorithms were the main sources of the observed discrepancies. The choice of simulation tool could thus influence the overheating risk assessment in flats, while the observed discrepancies in the simulation of air and heat transfer could have implications on other modelling applications.

Practical application: Technical Memorandum 59 issued by the Chartered Institution of Building Services Engineers may be widely adopted within the industry to assist the prediction of overheating risk in new dwellings. This work suggests that the choice of building performance simulation tool can greatly influence the predicted overheating risk. Furthermore, the differences identified in the modelling of heat transfer processes could also impact other modelling applications. Following these results, the need for detailed empirical validation studies of naturally ventilated homes has been highlighted.

A model for operating an energy hub-based multiple energy generation micro-grid is optimized using the demand response program. The optimized objective model is validated against energy demand of a residential building in Tehran, Iran. The mathematical model and optimal analysis of the proposed tri-generation micro-grid are implemented by using a real-world modelling and considering the constraints of the storage system, demand response program and the performance of the devices and the power and gas grids. The dynamic optimal operation model is prepared on the basis of the mixed integer linear programming on the subsequent day and is solved to minimize the costs of energy supply. To demonstrate the improvements, different scenarios are developed so that the renewable energy resources and storages are fed into the combined cool, heat and power system gradually. The results reveal that the inclusion of each element results in a significant improvement in the operational parameters of the micro energy grid. Scenario 1 includes a combined cool, heat and power system alone, Scenario 2 is supplemented with renewable wind and solar energy resources in addition to combined cool, heat and power system and Scenario 3 includes electrical, heat and cold storages in addition to combined cool, heat and power system and renewable energy sources. Scenario 4 is similar to Scenario 3 in terms of equipment, but the only difference lies in the use of the demand response program in the former. Total operational cost is 12.7% lower in Scenario 2 than in Scenario 1, 9.2% lower in Scenario 3 than in Scenario 2 and 8.6% lower in Scenario 4 than in Scenario 3.

Practical application: An optimized operation method is prepared for combined cool, heat and power systems running in different operation modes in which renewable energy sources and storages are added to the combined cool, heat and power and the demand response program is applied. The results reveal that the cost of energy supply, including the cost of electricity, gas and pollutant emissions, is reduced and the qualitative parameters of the operation, including efficiency and reliability of building micro-grid, are increased. The proposed algorithm and the evaluation method will enable building operators to plan demand response activity on the residential building in Tehran, while this can be extended to other buildings too.

Residential space and water heating account for 23% of UK final energy demand and combination gas boilers are the dominant technology. Performance gap issues in gas boiler systems have been reported, with previous studies unable to isolate or quantify root causes for performance issues, hampered by indirect and coarse measurement methods. Utilising high-frequency data, through state-of-the-art boiler diagnostics from 221 UK combination boilers, assumptions in efficiency standards are challenged. Total heating energy consumption and number of hot water tappings are in line with national expectations but the observed cycling behaviour of boilers gives cause for concern due to links with lower performance and higher emissions. Most combi-boilers appear oversized for space heating and despite available modulation are unable to prevent rapid on–off cycling. Per day, half of combi boilers studied average more than 50 starts and 70% of starts average less than 10 min during space heating operation. Cycling contradicts assumptions in efficiency testing standards, which assume steady state operation, weighted by full and part power measurements. Addressing oversizing and excessive boiler cycling provides an opportunity to quickly and significantly reduce emissions associated with heating, at low cost through the ongoing replacement of millions of boilers.

Practical application: Lessons learned from this research regarding the detrimental performance issues seen in gas combi boilers are directly applicable to the topics of boiler specification for building service engineers and installers, such as guidelines in CIBSE Guide A, ¹ CE54 Whole house boiler sizing method ² and legislation set out in BoilerPlus from the Department of Business, Energy and Industrial Strategy. Plant size ratio, radiator hydraulic layout and controls can all contribute to the rapid cycling seen in the data and can all be influenced by building service professionals. Boiler modulation range is also crucial and manufacturers need to be aware of the benefits of extending modulation in new products.

In recent years, buildings have become taller and wider. The conventional approach of one roped elevator car per hoistway seems increasingly impractical. The idea of ropeless elevators using linear motors was proposed more than 30 years ago, but it was merely treated as wishful thinking by the industry at that time due to lots of safety concerns. And discussion by the industry has mainly been qualitative in nature. In recent years, an international manufacturer announced the development of a prototype and the world's first installation may probably be open to public before the end of 2018. So far, academic studies have mainly focused on the study of linear motors with generic applications, while this paper focuses on the performance of the motor drive from an elevator's point of view. In this paper, we investigate the mechanism of the drive, and the linear permanent magnet synchronous motor and, by discretizing the equations of the full mathematical model, we fine tune the parameters and design suitable controllers. We evaluate its performance by computer simulation, based on the necessary kinematics of a real elevator, so as to arrive at some design guidelines. Finally, the most critical safety concern, i.e. free fall during a total power failure, is quantitatively studied by short circuiting all motor windings. Methods to achieve a reasonably constant and low descending speed, have been studied with parameters estimated analytically, and are verified by simulation. For the sake of illustrating the concept as an initial trial, simplified circuit models, controllers and sensors are all assumed as being ideal. It is hoped that this paper will stimulate the research interest of both the academic world and the industry, while the inclusion of more losses, armature reactions, and imperfections, etc., could be tackled in a further study.

Practical application : The application of one roped elevator car in taller and wider buildings seems increasingly impractical. This paper considers the analysis of the application of ropeless elevators using linear motors focusing on the performance of the motor drive from an elevator's point of view. A basic mathematical framework is developed to study and design the controllers and drive of a multi-car elevator system by using linear permanent magnet synchronous motors with emphasis on the elevator performance as a whole system. The paper is aimed at stimulating research interest to drive the appropriate analysis and application of linear permanent magnet synchronous motor driven ropeless elevators.

A method to evaluate the wind-driven ventilation potential of buildings is proposed and some schematic examples are given. Two indicators of such potential are put forward: the first concerning the pressure difference between spots (openings) on the facades and the second concerning the ratio between this pressure difference and a simplified measure of the pressure loss by the internal air flow. These indicators allow one to compare shapes and orientations and can help finding the most appropriate ones during a preliminary stage of the design of a naturally ventilated building. To present the proposal, a two-dimensional computational fluid dynamics parametric model of a schematic building is set, the parameters of which are the aspect ratio of the building's rectangular plan and the wind relative direction. The computational fluid dynamics simulations are supported by literature benchmarks and by qualitative experiments in a wind tunnel. Using this model, the pressure field is computed for 66 cases and their ventilation potentials are evaluated; some graphic outputs are then proposed for a preliminary understanding of the pressure field and of the resulting indicators. The optimal morphology given by such analyses is finally compared to that of some naturally ventilated existing buildings, including Iranian badgir towers.

Practical application : This paper provides graphs to predict a building's potential for natural ventilation thereby enabling a designer to determine the wind-driven ventilation in a building and evaluate the structure, optimise its orientation, its aspect ratio and opening positions. These can be used, for example, in the evaluation of naturally ventilated multi-storey rectangular plan buildings (that might employ hyper-ventilation or night cooling) or to evaluate possible passive ventilation strategies for existing buildings. With the support of these graphs, which can be used as computationally inexpensive and fast decision tools, it is possible to simulate configurations, considering the parameters that most influence natural ventilation.