Papers by Geoff Levermore
Building Services Engineering Research and Technology, Jun 13, 2013
Energy demand attributable to the operation of supermarkets is thought to be responsible for 1% o... more Energy demand attributable to the operation of supermarkets is thought to be responsible for 1% of UK greenhouse gas emissions. Current building regulations in the UK require the ''building related'' energy use of new commercial buildings to comply with particular requirements. Supermarket buildings are therefore modelled in considerable detail, according to these protocols to establish their predicted energy demand. Lighting, occupancy, and small electrical energy impacts are included in this modelling. However, a large gap is found between the design outputs of this modelling and the energy performance of the store in operation. One reason for this is that thermal interactions at the refrigeration cabinets are not included in this modelling, as refrigeration is classified as ''process energy'' rather than ''building related.'' This paper explores the comparative energy demands of supermarket retail floors simulated both with and without the cooling effect of refrigeration cabinets included in the simulation. The retail floor of a recently built supermarket is modelled using EnergyPlus. Practical applications: It has been shown that the energy demand of the retail floor of a new store could be reduced by 25% by improvement of the envelope, by halving ventilation rates and doubling insulation levels. This has been shown by simulation of the building energy flows with refrigeration cabinets included in the modelling (whereas these are currently excluded as process energy). Changes in modelling protocols, and regulations, to encompass refrigeration energy transfers, could reduce the national load, due to supermarkets, by at least 140 MW in 5 years. Energy costs to the retailer would be reduced by 20%. Additionally, the simulation has shown the contribution of rooflights to the reduction of energy demand to be lower than previously predicted, saving only around 1/3 of design expectations.
Building Services Engineering Research and Technology, Aug 1, 1998
Variable-air-volume (vAv) systems have become one of the most popular forms of air conditioning i... more Variable-air-volume (vAv) systems have become one of the most popular forms of air conditioning in recent years. They represent approximately 51% by value of the UK market for terminal units. Although VAV applications in the UK have recently declined with increasing interest in natural ventilation and low-energy buildings, terminal units are still used in many existing VAV air-conditioned buildings as well as some installations with displacement ventilation. VAV systems can be difficult to control for both maximum efficiency and stable operation, especially under part-load conditions. Steady-state terminal unit models are required for the network analysis of such systems to detect possible terminal unit 'starvation' and to determine part-load efficiency. This paper deals with the steady-state models of common vAv boxes. A future paper will describe the dynamic analysis. The measurements and modelling of three commercial VAV terminal units, two pressure-independent and one pressure-dependent, are described as well as the rig on which the measurements were made. These models are an improvement over the simple opposed-blade damper model that is currently in use as a simplification of the VAV terminal unit in simulation and network analysis programs. Depending on terminal unit design, the use of opposed-blade damper models could under-estimate the volume flow rate by as much as 65% where the damper is fully open under the same authority and percentage damper angle.
The project SoDa answers the needs of industry and research for information on solar radiation pa... more The project SoDa answers the needs of industry and research for information on solar radiation parameters with a satisfactory quality. The methodology is user-driven with a large involvement of users in the project, who will gauge the progresses and achievements. A prototype service will be developed, using Internet technology, that will integrate and efficiently exploit diverse networked information sources to supply value-added information. A multidisciplinary consortium has been assembled, which gathers companies and researchers with the necessary expertise in solar radiation and information and communication technologies. Customers and potential users are also represented as partners in the consortium via the involvement of commercial private vendors of solar radiation databases and of representatives of large research and development programs. A call is launched to recruit customers to assess the prototype. The project SoDa builds on the expertise gained in previous projects, such as the digital atlases MeteoNorm and European Solar Radiation Atlas, the Web servers Satel-Light and Helioserve, and the Guide of the Chartered Institute of Building Services Engineers of United Kingdom. Access to data and applications will be improved; efforts will be made on interpolation methods and satellite data processing to achieve better quality; emphasis will be put on applications to supply information actually needed by customers, instead of raw data.
Lighting Research & Technology, Dec 1, 2005
In this paper we have combined analytical analysis and inverse control theory to obtain an artifi... more In this paper we have combined analytical analysis and inverse control theory to obtain an artificial light-dimming model. With the advancement of direct digital control, the model based adaptive predictive control scheme is an attractive option. This paper presents a simple approach to developing the basis of the above concept. The adaptive neuro-fuzzy approach is a good choice for modelling these ill-defined systems, which are not easily subjected to conventional automatic control methods.
Building Services Engineering Research and Technology, Jan 18, 2012
A simple mathematical model of an urban canyon is developed. The canyon model consists of horizon... more A simple mathematical model of an urban canyon is developed. The canyon model consists of horizontal and vertical slabs providing thermal storage for heat and absorption of and shielding from solar radiation and long wave radiation to the sky. The model is compared to a horizontal slab in a rural location to examine the effect of the canyon shape. The results show the same trend as measurements by others, with increasing urban heat island (UHI) effect with increasing canyon aspect ratio. The model is then used to determine the maximum UHI effect by producing a simple algebraic equation. This compares well with measurements in Greater Manchester of canyon and rural temperatures although some empirical adjustments are required. The strong influence of cloud cover is shown by the model and measurements as are the canyon shape and the ground temperature. Practical applications: The model is simple and developed in terms applicable to building services engineers, using ventilation rates through the canyon. It also does not require more than the standard weather data available in a CIBSE Test Reference Year or a Design Summer Year. From this model, the UHI effect can be developed to adjust the data from a rural site to that of an urban and city centre site. This is useful for building designers to take account of the UHI effect which they cannot do at present. This would also be useful for UKCP09 data which have been released.
Building Services Engineering Research and Technology, Jun 29, 2010
As climate change predicts hotter summers and warmer winters in the next 100 years, buildings des... more As climate change predicts hotter summers and warmer winters in the next 100 years, buildings designed now as well as many existing buildings will need to cope with the future climate. The aim for building designers should be to provide buildings with comfortable environments for occupants without using excessive heating or cooling energy, which will exacerbate carbon emissions. This is particularly important for office buildings, as these are more susceptible to the effects of warmer temperatures, with their relatively high levels of internal heat gains. The productivity of occupants can also be affected if conditions of the workplace are not ideal. Using climate change data from UKCIP02 based on HadRM3 for three main sites in the UK (London, Manchester and Edinburgh), test reference years were selected for 2020s, 2050s and 2080s under various scenarios.1 Using a second-order room model, future energy usage for heating and cooling were estimated for office buildings complying with various editions of the UK Building Regulation, as a test of the buildings’ age against the effects of climate change. The findings show that the fall in heating energy demand is approximately equalled to the rise in cooling demand as a result of climate change up to the 2080s in Heathrow, Manchester and Edinburgh. Natural ventilation alone would not be able to provide enough summer cooling in the UK in the near future. New office buildings, complying with 2002 Building Regulations, perform significantly better than older ones, and their energy and CO2 emissions remain relatively constant with climate change. However, most of the existing office buildings in the UK are older buildings with lower standards of specification, and the challenge is to make these perform more efficiently. Retrofitting them to have similar properties to the 2002 Building Regulations will be sufficient to cope until 2080s, and increasing the ‘weight’ of the building enclosure will reduce the amount of cooling required. This paper also demonstrates that for all-air systems, it will be essential for fans to be sized correctly for the increasing cooling load with future climate. Practical application: This paper aims to provide a comprehensive study and understanding to how various different office buildings in the UK will cope with climate change, especially how climate change will affect the heating and cooling loads, as well as the associated CO2 emissions as a result of meeting the thermal demands. Using a second-order model, this study simulates an office room for three main UK locations, Heathrow (London), Manchester and Edinburgh, under respective climate change data for 2020s, 2050s and 2080s, comparing their thermal energy consumptions with current weather data. Apart from testing the office room with different orientations, construction thermal ‘weight’ and different future climate scenarios, the office room was also made to comply with various Building Regulations, which determine the permitted maximum U-values and glazing area of the external envelope, and the type of glazing used. This represents the office buildings currently in the building stock in the UK, and the analyses conducted are to examine how each will perform in the 21st century. The results from this study would be useful for building designers to know which aspects will affect energy consumption and thus CO2 emissions most in the future, and what should be done with the existing building stock, where most buildings were built to with higher U-values and single glazing, to make them perform efficiently in the face of a warmer climate. Would retro-fitting be adequate, or would they need to be demolished and re-built? As mechanical cooling becomes a necessity in the future, the energy required for running the fans also contribute greatly to the total CO2 emissions in office buildings in the future.
Lighting Research & Technology, Sep 1, 1997
... Much experimental work has shown a discrepancy between luminance measurement and brightness p... more ... Much experimental work has shown a discrepancy between luminance measurement and brightness perception. ... Two lamps are presented simultaneously in adjacent light booths. ... Lamps of higher colour quality require lower illuminance than do lamps of poorer colour quality. ...
Building Services Engineering Research and Technology, Feb 1, 1985
This paper starts by establishing that, under certain conditions, a theoretical group heating sch... more This paper starts by establishing that, under certain conditions, a theoretical group heating scheme is just viable compared to individual heating of dwellings. The paper then examines the fuel consumption of one typical group heating scheme and finds that it uses slightly less energy than that calculated for individual heating of the dwellings, although the energy consumed in both cases could well be reduced by modern design. A further analysis, of the consumption data from 69 Inner London schemes, shows that domestic hot water generation is a source of inefficiency. It is proposed that this could be improved by individual generation in the dwellings with the group scheme providing space heating only.
Building Services Engineering Research and Technology, May 1, 1986
This paper takes the standard steady state heat supply and loss equations used in many heating te... more This paper takes the standard steady state heat supply and loss equations used in many heating textbooks and applies them to a compensator controlled heating system. It then develops the equations to consider casual gains. Sensitivity analysis is carried out on emitter and boiler sizes. It is found that: heating systems without internal sensors can utilise up to 30% of casual heat gains to reduce system heat output; that the heat emitter size is of key importance to efficient control; that a nonlinear compensator algorithm is required to maintain constant room temperatures. To show the effectiveness of a compensator, a system with a compensator is hypothetically compared with one with only a boiler thermostat at a constant setting.
Building Services Engineering Research and Technology, Jun 13, 2013
Representative, site-specific weather data is a key requirement for building performance simulati... more Representative, site-specific weather data is a key requirement for building performance simulation. In the UK, such data is available in two formats, Test Reference Years for analysing building services loads under ‘typical’ year conditions and Design Summer Years for estimating summer discomfort of naturally ventilated and free-running buildings. Currently, Design Summer Years are determined as a complete year based on the rank of the average dry bulb temperature from April to September. The simplicity of this approach does not take into account extreme temperature values in individual months or the incident solar radiation, both of which are however of great significance for the summer overheating performance of a building. This paper analyses the implications of this simplified approach for the resulting data. It is shown that there is no consistent relation between the Design Summer Years and the corresponding Test Reference Years and that, for some sites, building performance simulations using Design Summer Year files deliver unreliable results. Practical application: This paper demonstrates that the current approach for deriving Design Summer Years (DSYs) can lead to data series that are not representative for near-extreme summer conditions at a given location. It highlights that a new approach for deriving near-extreme summer years for building performance simulation is needed in order to overcome the inherent shortfalls of the current DSY data.
Routledge eBooks, Jul 4, 2013
Ashrae Transactions, 2005
Duct loops are often used in VAV air systems to save energy, ensure a balanced air delivery and s... more Duct loops are often used in VAV air systems to save energy, ensure a balanced air delivery and simplify fabrication and construction. Duct loop performance is more complicated than that for a standard radial tree network and simulation methods are required. Such simulation is examined. Part-load and asymmetric duct-loops are also analyzed where numerical methods are required rather than dividing the symmetrical duct in two for easy calculation. The numerical method is discussed. The full and part-load simulation of duct loops and comparable networks are then considered. Significant savings in fan power are possible compared to radial tree and two-branched networks but the non-duct pressure losses (coils, filters etc) will determine the actual system saving in each case. However, duct loops do require a larger amount of sheet metal in most cases for which the costs will count against the duct loops. However, economics are not considered in any depth in this paper.
Building Services Engineering Research and Technology, Feb 1, 1996
An initial survey has been conducted to assess a self-administered questionnaire, fingerprint and... more An initial survey has been conducted to assess a self-administered questionnaire, fingerprint and liking score which are aimed at quantifying, in a simple manner, occupants' perceptions of their interior environments. 450 questionnaires have been analysed. The average liking scores for groups of occupants range between -14% and +19%. The questionnaire responses have been found to be consistent in two test-retests and in agreement with an earlier independent survey. The results from four groups of occupants in four different buildings, (208 responses), naturally ventilated and air conditioned, are discussed in detail. In general there was agreement between the liking scores and building sickness scores but two buildings, each with a Building Sickness Score of 1.7, had liking scores of +19% and +1%. The questionnaire also revealed that office temperature, occupant health, and daylight were important factors, whereas appearance of the building, room colours and attractiveness were the least important factors. Although minor modifications to the questionnaire are considered, and have been implemented in the PROBE project, it is hoped that the questionnaire will become a useful management and design tool.
Building Services Engineering Research and Technology, Feb 1, 1995
With the increasing use of building energy management systems (BEMS) and serially interfacable ut... more With the increasing use of building energy management systems (BEMS) and serially interfacable utility meters, performance lines and energy signatures can be very useful management tools. This paper proposes models of intermittent heating, taken from the CIBSE Building Energy Code, boiler efficiency and compensator control to give a better understanding of energy signatures, the heating plant and its control. Using these models the seasonal efficiency of the boiler is determined as 57%, that for the compensator as 70%, and the intermittent heating saving 17% for an example two-storey open-plan office building.
Building Services Engineering Research and Technology, Mar 12, 2010
Good building design aims to balance providing a comfortable internal environment for as much of ... more Good building design aims to balance providing a comfortable internal environment for as much of the time as possible within a variety of constraints. An important factor is the expected weather, but in a changing climate this poses additional challenges to engineers and architects. This paper examines the effects of increased external temperature on the size of the central air conditioning and heating plant for an example building. It is found that for each 1°C rise in external temperatures, the peak cooling load increases approximately by 10%, the chiller power by 14% and fan power for distribution by 30-50%. These are relatively large increases in power needed to counteract rising external temperature and the paper considers the choice of risk level for sizing building plant. From HadRM3 data, the future frequency distribution of higher external temperatures is examined to evaluate the effects on plant size of designing to a fixed percentile of risk. Projected changes in absolute humidity are also discussed. Practical applications: Climate change is an important topic for building services engineers, resulting in the UK in the new, performance-based Building Regulations Part L. New, future weather data will also become available with different climate change scenarios. This paper examines the implications of both climate change and the risk level on the peak load for natural ventilation or air conditioning and heating that is used in the design of systems.
Lighting Research & Technology, Dec 1, 1995
An experiment was carried out to assess the visual perception of a blue-glass tungsten lamp in co... more An experiment was carried out to assess the visual perception of a blue-glass tungsten lamp in comparison with an ordinary tungsten lamp. The lamps were simultaneously presented in adjacent light booths to observers who were asked to balance the lights for visual equality by varying the supply voltage to the ordinary tungsten lamps. Results show that on average the observers would prefer 35.8% less illuminance from the enhanced blue sources. The performance of a visual task was maintained under the blue-glass lamps despite lower illuminance, and the majority of observers expressed preference for the luminous environment of the enhanced blue light for their workplaces. Neither V(λ) based photometry, Berman's pupil lumens, nor Lynes' photometric anomalies could account for the experimental results.
Building Services Engineering Research and Technology, May 1, 2002
In manual heat gain and heat loss calculations the standard linear ventilation and infiltration h... more In manual heat gain and heat loss calculations the standard linear ventilation and infiltration heat loss formula (/)NV(tai tao), (with a suitable factor to relate to comfort temperature), is used. In the 1986 CIBSE Guide Section A8, Summertime temperatures in buildings, a limiting ventilation heat loss formula is used as the air change rate, N, increases, but, as with older guides, there is no reference or explanation of its derivation,1 although the 1970 Guide offers some explanation. This limiting equation is not used in the 1999 Guide A, Environmental design which is unfortunate. This paper analyses the ventilation heat loss based on a log mean temperature difference heat transfer approach which also shows a limiting heat loss effect like the A8 equation. It is also suggested that an admittance value should be used instead of a constant heat transfer coefficient which gives greater insight into the heat transfer process. Significant reductions in the heat transfer process are found at relatively low air change rates using the more correct formulae, which could have implications for summer natural ventilation, during both day and night.
Building and Environment, Mar 1, 2012
This paper addresses the dual challenge faced by Burkina Faso engineers to design sustainable low... more This paper addresses the dual challenge faced by Burkina Faso engineers to design sustainable lowenergy public buildings while still providing the required thermal comfort under warmer temperature conditions caused by climate change. In this article, we discuss current and potential future energy demand for public buildings air conditioning in the context of climate change. Past and projected future trends of electricity demand for air conditioning in public buildings from 2010 to 2080 have been investigated. Moreover, this paper highlights the fact that the predicted mean temperature using climate change SRES scenario B2 will increase by about 2 C by 2050 which can cause a significant increase in air conditioning energy consumption. This paper then considers the impact of different shading devises and building envelopes characteristics on the demand for airconditioning in Burkina Faso public buildings. It is estimated that with climate change, in order to maintain a thermally comfortable 25 C inside public buildings, the projected annual energy consumption will have to increase by 56% and 99% respectively for the period between 2030 to 2049 and 2060 to 2079 compared to the base situation (energy consumption between 2010 and 2029). Moreover, the results have shown that shading devices could reduce the cooling load by up to 40%. Therefore shading devices could play a significant role in climate change adaptation in the built environment for Burkina Faso.
Building Services Engineering Research and Technology, Feb 1, 1995
The CIBSE Building Energy Code Part 2(a) was devised as a method of assessing the energy performa... more The CIBSE Building Energy Code Part 2(a) was devised as a method of assessing the energy performance of designs for heated and naturally ventilated buildings. This paper presents the authors' experience in teaching the use of the Code, primarily to building services undergraduates, and the value of developing this into an educational tool to raise students' awareness of energy issues in buildings. There are a number of other significant educational benefits. Projects along these lines could be adapted to suit other professions in the building industry. Some example results are presented, together with some broad conclusions drawn by both students and the authors on the validity of the Code as a general tool. Its strengths and weaknesses are discussed and further work suggested.
Building Services Engineering Research and Technology, Jun 11, 2014
Typical weather data (TWD) consists of 8760 values of various selected meteorological parameters ... more Typical weather data (TWD) consists of 8760 values of various selected meteorological parameters such as ambient temperature, solar radiation, relative humidity and wind velocity, and are originally derived from long-term data. In this paper, TWDs have been generated, using three different methodologies, from hourly meteorological data measured in Seoul, Daejeon, Daegu, Gwangju, and Busan. The aims of this study were to compare the simulation results from the three methodologies (ISO Test Reference Year, CIBSE Test Reference Year, and Typical Meteorological Year) with those from individual years and their long-term means to assess the important five components of the building envelope (wall-to-window ratio, window overhang, window transmissivity, window U-value, and wall U-value) for the influence on the heating and cooling load and to study the influence of the different weather parameters (temperature and solar radiation). Results of the comparison show that predicted monthly load and energy consumption profiles from the TWD tended to follow the long-term mean quite closely. The load calculations vary almost linearly as the building envelope components varied apart from the window U-value. The yearly average values of mean bias error and root mean squared error for the heating and cooling loads were evaluated for the three TWDs and long-term measured meteorological data. Practical application: This paper will enable engineers and building designers of buildings in South Korea to assess the heating and cooling loads with more confidence. The paper will enable designers to use the appropriate weather data when using computer simulation for the design. The designer will also be able to assess the energy efficiency better.
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Papers by Geoff Levermore