Building Services Engineering Research & Technology

Building dynamics are key to summer overheating, plant sizing and ventilation strategies. Building designers need to consider the thermal mass of a building explicitly to understand fully a building’s response. Simulation programs readily show the dynamic responses but they are deduced from the solution of embedded intrinsic differential equations without simple understanding for initial design and appreciation. The admittance method gives such a simple understanding but the thermal mass effects are not obvious. Added to which the admittance is limited to a regular 24 h cycles of heat gains and losses. The Chartered Institution of Building Services Engineers (CIBSE) response factor is an approximation to the response of a building but it is limited to defining just slow or fast responses. Frequently, designers refer to heavyweight and lightweight buildings or even long and short time constants. The latter are simple and understandable. This paper explores the time constants and derives a simple multiple time constant equation to indicate thermal storage in a building. It is suggested that the simple time constant for building components is added to the data in the next edition of the CIBSE Guide A. This will aid designers in understanding a building’s winter heating and potential summer overheating and plant size implications.

In a hot and humid tropical climate, natural ventilation brings high levels of moisture into dwellings that, together with occupant activity, can result in very elevated internal relative humidity levels. Coupling these high relative humidities with high internal air temperatures creates occupant thermal discomfort, which is typically ameliorated in the tropics using energy-intensive air conditioning systems. This paper has investigated the potential benefits for thermal comfort and energy usage of applying the German Passivhaus standard to tropical dwellings. By creating a super insulated and air-tight envelope, the Passivhaus standard reduces fabric heat transfer, controls air infiltration and provides low-energy comfort. Applying this approach to a tropical terraced house might be effective but could, potentially, have an adverse impact on mechanical cooling demand. This study took an actual terraced property in Jakarta, Indonesia and thermally modelled its performance as insulation and airtightness levels were incrementally improved up to the Passivhaus standard. Field measurements in the dwelling of air temperature and relative humidity were used to validate the thermal model of the existing house. The validated model then tested the feasibility of meeting the Passivhaus energy standard for cooling in the modified tropical house. Simulation allowed the effects of air conditioning (AC) and dehumidifiers on thermal comfort and cooling loads to be investigated. The research develop the Passivhaus building model that had the floor insulation removed to let the ground floor act as a thermal sink and potentially provide radiant cooling. Analysis revealed that the building’s predicted air temperatures were affected in a beneficial way by having the Passivhaus without floor insulation.

Practical application: Cooling in hot and humid tropical region is an energy-intensive approach. Design approaches that can bring comfort and save energy for the occupant are essential. The success of Passivhaus standard in mild climate might be transferable to bring comfort in tropical housing. Best practice can be developed by analysing the Passivhaus building performance in hot and humid tropical region.

With the help of building diagnostics, the causes and solutions to complex problems in buildings can be determined. In central and greater London, an increasing number of cases of chronic, year-round, overheating in buildings have been reported. We present three cases of unexpected temperatures in multi-storey residential buildings. Detailed analysis and modelling of these scenarios have led to an investigation of whether the way in which infiltration is currently modelled in building performance simulation may be exerting a pronounced effect on the results of overheating studies. An EnergyPlus model, of one of the dwellings in a multi-residential building in London, was created to investigate the influence of infiltration and exfiltration pathway assumptions on the prediction of overheating. The simulation results were compared to empirical data and show that the predicted indoor temperatures are highly sensitive to how the infiltration airflow network is modelled. The findings of this study have been used to provide practical guidance for modellers and building designers on critical aspects to consider when creating building performance simulation models to ensure more reliable outcomes.

This paper uses a case study-based approach to empirically investigate the relationship between indoor environment and workplace productivity in two contrasting office environments: one naturally ventilated, the other mechanically ventilated. Environmental parameters were continuously monitored over 19 months. Transverse and longitudinal surveys recorded occupants’ perception of their working environment and self-reported productivity, while performance tasks (numerical and proofreading) measured cognitive capability as proxy for measured productivity. Indoor temperatures and CO₂ concentrations were found to be higher and more variable in the naturally ventilated office. However, the correlation between occupant perception of their indoor environment and perceived productivity was stronger in the mechanically ventilated office. Occupants of the naturally ventilated office were found to be more tolerant of their environment than their counterparts in the mechanically ventilated office. Task performance was affected by indoor environmental conditions such as indoor temperature and CO₂ concentration. Interestingly in the naturally ventilated office, the median scores were up to 12% higher for tests conducted at CO₂ concentrations <1400 ppm, compared to those conducted above 1400 ppm, whereas in the mechanically ventilated office, this threshold was only 1000 ppm.

Energy consumption in buildings varies considerably depending on type and usage. However, monitoring and regulation of electrical power consumption due to user-related activities are not presently embedded in current English Building Regulations. These energy uses include lifts, server rooms, and small power loads, and are collectively referred to as unregulated energy usage. As part of a larger study of unregulated energy usage in university campus buildings, this paper describes the development and demonstration of a methodology for quantifying unregulated power usage using Building Energy Management System data for a case study university. The methodology was applied to four different buildings. This approach was applied to a Chemical Laboratory, a Physical Science Laboratory, a Library and an Administration Office. The results obtained revealed that electrical consumption was consistently much higher than traditional benchmarks suggest as being normal, particularly within the laboratories. Additionally, within the specific unregulated electricity case study, four rooms in the Physical Science Laboratory indicated very high unregulated electricity usage figures, averaging at 89 kWhm⁻² per annum across just four rooms.

Practical application: Unregulated energy research, within the Higher Education Sector, is undeveloped. Previous literature focuses on specific areas of unregulated energy, such as equipment usage. However, analysis based on different room types has not been completed on a wider scale. Hence, there is a gap in the current research. This research shows analysis of unregulated energy in different university buildings. It develops a methodology to further understanding on this undeveloped area. Additionally, it advises that unregulated energy must be calculated during a building’s design stage. By using a selection of case studies, this research furthers understanding on the overall effects of unregulated energy.

In dwellings connected to district or communal heating schemes occupants are commonly charged based on actual heat consumption, providing a direct link between heat consumption and weekly heating cost. This article investigates how the use of fixed-rate, shared-cost charging without dwelling-level metering affects the heating and controls use in communal network social housing. Living room and radiator temperatures in 50 flats were monitored over a winter heating season and occupants surveyed at monitoring install and removal. The primary stated and observed heating strategy was to leave the heating always on and control through the radiator thermostatic radiator valves. Of people who used timer control, total heating hours reduced with increased frequency of manual intervention. Mean indoor temperatures up to 27.7°C were observed, implying many residents are adapted to higher indoor temperatures. Thus, the current model encourages wasteful behaviour and education on use of controls is key to transitioning residents to charging for actual heat use.

Practical application : This article intends to inform the landlords of communal network social housing schemes on the impacts that shared-cost recovery methods of charging for heat has on heating and controls use. This charging method can impact the behaviour of the network occupants resulting in higher heat consumption, overall higher heating costs and subsequently higher carbon emissions from the site if occupants are not adequately trained in how to operate their heating effectively. Where similar charging methods are implemented, the article hopes to inform operators of the potential vulnerabilities of the network occupants to changes in the method of charging for heat.

Boilers in hydronic heating systems are the norm in the UK. Through case study analysis, covering four houses with gas central heating systems for over one year and utilising novel monitoring of the on-board diagnostic data of the boilers, performance issues were identified in this mature technology. ON/OFF cycling behaviour and oversizing were prevalent with boilers consistently unable to modulate low enough to match the building space heating demand. Cycling behaviour resulted, known to be detrimental to efficiency, with the majority of boiler operations lasting less than 10 min. Targeted case study analysis of incumbent technologies, such as boilers, utilising the latest in data collection techniques and connected appliances provides a cost effective insight to broader issues. Implications for domestic energy demand range from incremental improvements in boiler system efficiency by addressing cycling to the updating of building energy assessment models (e.g. Standard Assessment Procedure) to reflect and reward the benefits of good installation practices. An improved understanding of boiler operation may support improved product design and installation practices and are beneficial to the next generation of domestic heat, such as heat pumps. By undertaking continued in situ analysis of the incumbent technology, a more thorough foundation for the future can be ascertained.

There is a policy-driven focus, at present, on improving the energy performance of buildings. However, energy-related issues alone do not capture the full impact of buildings on occupants and the wider environment. The performance of a building also includes occupant wellbeing and indoor environmental quality. Specifically, in schools, indoor environmental quality (thermal comfort, indoor air quality, lighting and acoustics) is an important aspect. Additionally, the issue of the ‘performance gap’, generally focused on energy, also affects indoor environmental quality parameters and needs to be addressed holistically. This paper reports on a holistic building performance evaluation covering aspects of energy, thermal comfort, indoor air quality, lighting and acoustics. It assesses the performance issues and inter-relationships between energy and indoor environmental quality in a recently built school campus in London. Based on the evidence collated from this case study and supplementary literature, the endemic issues and constraints within the construction industry are explored, such as inappropriate design calculations and resistance to new low-carbon technologies. Further, lessons for improved performance in the design, operation and maintenance of schools are highlighted such as factoring in the changing building use trends during design and the significance of optimal operations and maintenance of building systems for better energy and indoor environmental quality performance. This study shows that if the building design focus primarily remains on energy, unintended consequence of indoor environmental quality underperformance may occur where there are conflicts between energy and indoor environmental quality objectives. An integrated approach to building performance can help address this issue.

Practical application : There are often conflicts between energy efficiency and indoor environmental quality (IEQ) objectives in building design and operation. Most building performance evaluations are primarily focused on one set of these performance criteria. This building performance evaluation was done with an integrated energy and IEQ perspective. The study identifies the causes of underperformance in energy and IEQ in a recently built school in London. Some of the findings from this study provide lessons that are relevant across the industry for the delivery of low-carbon and healthy buildings. These lessons include methods to further strengthen the policy frameworks and design protocols along with overall improvements in the processes followed during design, construction and operation of schools and other non-domestic buildings. The paper can also inform building designers, contractors and facility managers about the ways to reduce the performance gap and achieve energy targets without unintended consequences for indoor environment.

The existing residential building stock in many industrialized countries is large but extremely energy inefficient, despite the existence of energy directives that apply mostly to new construction. Prefabricated building refurbishment for energy upgrading is a viable option for the existing building stock, but solutions need to adapt to each case and usage in order to respond to specific requirements. The “RECO2ST” project (Horizon 2020) is used as example of a forecast methodology that can help achieve nearly zero energy refurbishments, through selection of innovative modular elements for the opaque and transparent areas of the building envelope, covering diverse energy reduction strategies while improving thermal comfort and indoor air quality. This integrated approach is not usual in the field. The Technical Note studies a series of facade and active window technologies that supply climate strategies such as insulation, heat recovery and ventilation. The methodology is demonstrated for three sample cases using a typical refurbishment scenario. It is evaluated through energy simulation and analysis of improvements in thermal comfort and indoor air quality indicators.

Practical application: The methodology helps to reduce guesswork for actions to be taken in order to refurbish and upgrade the existing housing stock to comply with current energy directives. It takes into account at the same time energy performance and user comfort, as expressed through indoor air quality.

Plants are utilised in many forms within indoor environments, from simple houseplants to complex and species-rich green walls. Plants offer multi-faceted services indoors including pollutant removal and reductions in building energy consumption. This review firstly identifies – by critical assessment of the literature – pollutants which are currently measured at harmful concentrations indoors – classifying them as ‘2019’s priority pollutants’ and providing thorough health assessments of each. Secondly, the authors present which indoor plants have been shown to effectively remove ‘2019’s priority pollutants’ and direct future research onto any that have not been investigated. Thirdly, the authors consolidate the current research presenting why plants should be considered a building service.

Practical application : Plants are commonly used inside indoor environments. However, the benefits they bring are often overstated. This review paper looks to consolidate the current academic research on the various services plants can provide indoors including pollutant removal and relative humidity regulation. The authors hope that the paper can be used to inform and educate building service engineers and alike on the current state of play concerning indoor plants.