The environmental concerns of C02 emissions resulting from the increasing consumption of fossil fuels over the past decades has called for greater utilisation of renewable energy resources such as solar energy, wind power and biomass energy. Currently, biomass combustion is the dominant conversion technology that is used to extract energy from biomass feedstock at all scales. However, biomass combustion can lead to significant amounts of gaseous (e.g. NOx, CO) and particulate matter (PM) emissions, which is a particular concern for simple and small scale biomass combustion stoves and boilers. The present PhD work aims to achieve low emissions of NOx, CO and PM with a 50kW commercial boiler burning different woody and non-woody biomass pellets by the use of combustion modifications and a particulate removal unit. The combustion performance and emissions of NOx, CO and PM of the boiler were experimentally investigated with three different types of woody and non-woody biomass fuels. Different operating conditions for the minimisation of NOx and CO emissions, including the 'air staging' method and the novel 'reverse flame box' system, have been studied. An innovative particulate filter unit was installed in the flue path of the boiler as a means to reduce PM emissions. CFD modelling of the tested boiler has been carried out and the simulation results have been presented and discussed in this thesis. The experimental results showed that the modified biomass boiler could handle woody biomass pellets while maintaining low levels of CO and NOx emissions. It could also handle non-woody biomass pellets if appropriate additives are added. An approximate 40% NOx reduction was achieved when the boiler was incorporated with a novel low emissions strategy termed as a 'reverse flame box', compared to the original boiler design. With the use of the innovative particulate filter unit, the PM emissions were reduced to about 1 mg/m3, which shows the particulate filter unit reduces PM emissions by over 98%. For the CFD simulation, the modelling results showed the correct trends, although it did not predict adequately the degree to which the boiler configurations affect the emissions.

Home Energy Ratings (HERs) have been a factor in reducing emissions from UK housing stock over the last twenty years. The new EU Energy Performance of Buildings Directive requires the contribution from Low and Zero Carbon Technologies (LZCs) to be included in such ratings. However, LZCs do not behave in the same way as fossil-fuelled energy sources and the requirement raises several questions about the existing philosophy of energy ratings. This thesis aims to answer these questions in a practical way by developing and testing solutions as a basis for a new methodology for assessing examples of LZC output in the UK's NHER, to permit straightforward comparison and quantification of the merits of each technology. The example technologies of solar domestic water heating, photovoltaic cells and micro-combined heat and power were chosen to illustrate the scope for comparison within a HER in terms of location, demand matching, and export, from amongst the technologies likely to be in general use in future. Hourly models of these LZCs have been investigated, selected and adapted for use in the energy model underlying the HER, then simplified to a format appropriate foruse ill a HER, preservmg the most unportant details. The results of this simplification exercise were to give the variables that most influence the performance of each chosen LZC technology. In each case, variables dependant upon location were amongst those that had the most significant effect on yield. It is desirable to use different criteria when rating renewable energy than with fossil energy. Where cost and quantity of fuel used are the main issues in rating conventional technologies, demand matching and the emissions reduction potential of export are major concerns in rating LZCs, so to approximate these external factors, selected historical data describing national profiles of electricity demand and generation mix have been adapted for use with the LZC models alongside generated domestic electricity demand profiles. These have been used in evaluating the worth of replacement energy as it changes over time. The profile of yield and export for each LZC type and combination can be compared to the domestic demand and national demand profiles respectively. For each of these comparisons, a factor describing the fit of each supply profile to the demand has been derived. These factors have been applied along with multiple regression analysis in simplifications of the models. Equations have been derived which best capture the expected energy performance of the LZC types for all ordinary situations, 'and are appropriate for use in HERs

The use of thermal energy storage in buildings is well understood but contemporary buildings with highly insulated, lightweight construction have low thermal inertia. This causes them to respond rapidly to external temperature changes, which results in significant internal temperature fluctuations and overheating. This research addresses this problem by developing a thermal interactive wall-lining through the inclusion of phase change materials. Phase change materials (PCMs) not only absorb sensible heat but also absorb and release latent heat during phase transition. This research set out to determine if it is possible to locate phase change materials on the surface of a room and if they can effectively improve the thermal performance of a room. Using the scientific method the suitability of different types of PCMs was investigated for inclusion within a vinyl matrix. Experiments evaluated the maximum quantity of PCM loading and thermal analysis identified the largest potential heat storage capacity for the phase change wall-lining. Following successful laboratory experiments a pilot scale prototype phase change wall-lining was manufactured and tested. The test involved an experiment comprising two thermally matched chambers to evaluate the thermal performance of the phase change wall-lining in a controlled environment. The results demonstrated the phase change wall-lining can reduce internal temperatures by more than 2°C and delay the time taken to reach extreme temperatures. The effect of different air flow rates on the ability to charge and discharge the phase change wall-lining have been evaluated to identify the required operating criteria for use in buildings. This research has developed an innovative phase change wall-lining that reduces internal peak temperatures, minimises diurnal temperature fluctuations by storing excess heat and improves the thermal comfort. The outcomes provide a greater understanding of the interaction between air and PCMs when located on the surface of a room, and indicate that such materials have the potential to improve thermal performance of new and existing buildings.

In recent years, operational prediction and optimisation of heating, ventilating and air conditioning (HVAC) systems and central plant to minimise the energy required to maintain building indoor conditions have become increasingly important. To effectively design and implement an energy management program for building energy systems, a simulation study must be performed. This thesis describes research conducted into the development of a modular simulation program for analysing the performance of HVAC systems and central plant. The computer program uses a quasi-steady state modelling approach and is able to simulate a wide variety of systems which are configured using available component models. Steady state mathematical models of HVAC components are developed using fundamental heat and mass transfer principles, laws of conservation of mass and energy and where appropriate empirical data. The carponent models are formulated to allow for the effects of various control strategies on the performance of systems and plant to be investigated. The program is applied to simulate a part of the Collins' Building variable air volume (VAV) air conditioning system and a hypothetical central cooling plant. The results of the simulation exercises are presented and analysed. The issue of validation and building energy simulation models is discussed. Conclusions are drawn and recommendations for further work are made.

In the UK, buildings contribute around one third of the energy-related greenhouse gas emissions. Space heating and cooling systems are among the biggest power consumers in buildings. Thus, improvement of energy efficient of HVAC systems will play a significant role in achieving the UK carbon reduction target. This research aims to develop a novel Building Energy Management System (BEMS) to reduce the energy consumption of the HVAC system while fulfilling occupants’ thermal comfort requirements. The proposed system not only considers the occupants’ adaptations when making decisions on the set temperature, but also influences occupants’ behaviours by providing them with suggestions that help eliminate unnecessary heating and cooling. Multi-agent technologies are applied to design the BEMS’s architecture. The Epistemic-Deontic-Axiologic (EDA) agent model is applied to develop the structure of the agents inside the system. The EDA-based agents select their optimal action plan by considering the occupants’ thermal sensations, their behavioural adaptations and the energy consumption of the HVAC system. Each aspect is represented by its relevant objective function. Newly-developed personal thermal sensation models and group-of-people-based thermal sensation models generated by support vector machine based algorithms are applied as objective functions to evaluate the occupants’ thermal sensations. Equations calculating heating and cooling loads are used to represent energy consumption objectives. Complexities of adaptive behaviours and confidence of association rules between behaviours and thermal sensations are used to build objective functions of behavioural adaptations. In order to make decisions by considering the above objectives, novel multi-objective decision-making algorithms are developed to help the BEMS system make optimal decisions on HVAC set temperature and suggestions to the occupants. Simulation results prove that the newly-developed BEMS can help the HVAC system reduce energy consumption by up to 10% while fulfilling the occupants’ thermal comfort requirements.

This thesis details the development and testing of a metamodel-based building optimisation methodology dubbed thermal building optimisation tool (T-BOT), designed as an information gathering framework and decision support tool rather than a design automator. Initial samples of building simulations are used to train moving least squares regression (MLSR) meta-models of the design space. A genetic algorithm (GA) is then used to optimise with the dual objectives of minimising time-averaged thermal discomfort and energy use. The optimum trade-off is presented as a Pareto front. Adaptive coupling functionality of the building simulation program ESP-r is used to augment the dynamic thermal model (DTM) with computational fluid dynamics (CFD), allowing local evaluation of thermal comfort within rooms. Furthermore, the disconnect between simulation and optimisation induced by the metamodeling is exploited to lend flexibility to the data gathered in the initial samples. Optimisations can hence be performed for any combination of location, time period, thermal comfort criteria and design variables, from a single set of sample simulations; this was termed a “one sample many optimisations” or OSMO approach. This can present substantial time savings over a comparable direct search optimisation technique. To the author’s knowledge the OSMO approach and adaptive coupling of DTM and CFD are unique among building thermal optimisation (BTO) models. Development and testing was focussed on hospital environments, though the method is potentially applicable to other environments. The program was tested by application to two models, one a theoretical test case and one a case study based on a real hospital building. It was found that variation in spatial location, time period and thermal comfort criteria can result in different optimum conditions, though seasonal variation had a large effect on this. Also the sample size and selection of design variables and their ranges were found to be critical to meta-model fidelity.

The aim this work was to investigate the effect smart heating control systems have on the energy performance in domestic homes in the UK. An experimental investigation was conducted of three case study buildings which were selected with different constructions and occupancy patterns to represent a cross section of the typical UK housing stock. Temperature data loggers were deployed in each home from 1 February until 31 April 2014 and these logged the internal temperature of the living room, kitchen and master bedroom at 5 minute intervals. A numerical analysis using IES VE (Integrated Environmental Systems Virtual Environment) dynamic thermal modelling software was undertaken of these three case study buildings with the results from the experimental investigation used to provide validation that the thermal performance of the dynamic thermal models was the same as the case study buildings, within experimental tolerances. The thermal performance for each case study building was compared to the CIBSE (Chartered Institute of Building Service Engineers) recommended guidelines for internal thermal comfort temperatures and consistent underheating in each case study building was identified. One dynamic thermal model was selected and taken forward for modifications to be made to the heating control system, with the single zone thermostatic control system being replaced by a 2 zone thermostatic control system and finally a multi zone thermostatic control system. Three thermostat schedules were investigated for the zoned control systems, the first being a 9-5 working schedule assuming the occupants are out of the house between those hours, an always occupied schedule assuming some level of occupation through the day and a nightshift schedule assuming a shift workers pattern not following a traditional Monday to Friday 9 – 5 working week. The study found that increasing the zoning of the control systems did not yield energy savings in every case but did increase the comfort conditions for the occupants and the degree of control the occupants had in their building. The occupancy pattern was found to affect the performance of the zonal heating strategy.

In hot climates ventilation can be a useful means of cooling dwellings, if the outside air be cooler than that inside the dwelling. Often, in hot regions the outside air is so hot during the day that cooling by ventilation is of no benefit until the evening when the outside air gets cooler. Ventilation can then be beneficial, and can be promoted by a sun-warmed cavity or 'solar chimney' added to a building on the sunward side. The cavity may be of any material of high thermal capacity. Heat from the sun is stored within the walls forming the cavity and heats the air within. The cavity is closed at the top and bottom by dampers. These, when opened in the evening, allow the buoyant hot air contained within to rise, drawing cooler outside air into the building. This process continues until the stored energy is consumed. The performance of a typical cavity to induce ventilation into a house is studied experimentally and theoretically. The measurements are made on a full-scale model in the steady state. Cavity width and air inlet area to the cavity are important parameters in this study. Measurements are made on the temperature and velocity of the air. Observations on air flow patterns in the room and the cavity are made. A steady state analysis is compared with the measurements. A dynamic model is developed based on a finite difference technique, and used to examine the performance of the cavity in various circumstances. The results show that air movement can be produced by a sun-warmed cavity if the dimensions of inlet and cavity width are kept at certain values.

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Sectoral energy consumption analyses clearly indicate that building sector plays a key role in global energy consumption, which is almost 40% in developed countries. Among the building services; conventional heating, ventilation and air conditioning (HVAC) systems have the greatest percentage in total energy consumption of buildings. According to the latest research, HVAC is responsible for around 40% of total building energy consumption and 16% of total global energy consumption. In this respect, decisive measures need to be taken to mitigate the energy consumption due to HVAC. The research carried out within the scope of this thesis covers innovative heating, cooling and ventilation technologies for low-carbon buildings. The novel technologies developed are introduced and investigated both theoretically and experimentally. The results indicate that optimised HVAC systems with waste heat recovery have a significant potential to mitigate energy consumed in buildings, thus to halt carbon emissions. Especially plate-type roof waste heat recovery units are very attractive for the said hybrid applications with a thermal efficiency greater than 88%. The said systems are also promising in terms of overall coefficient of performance (COP). The average COP of plate-type roof waste heat recovery unit is determined to be about 4.5, which is incomparable with those of conventional ventilation systems. Preheating performance of fresh air in winter season is found to be remarkable. Comprehensive in- situ tests clearly reveal that the temperature rise in fresh air is found to be around 7 °C. Plate-type roof waste heat recovery units also provide thermal comfort conditions for occupants. Indoor CCE concentration is observed to be varying from 350 to 400 ppm which is very appropriate in term of air quality. In addition, average relative humidity is found to be 57%, which is in the desired range according to the latest building standards. Desiccant-based evaporative cooling systems are capable of providing Abstract desired indoor environments for occupants as well as having considerably high COP ranges. An average of 5.3 °C reduction is achieved in supply air temperature by utilising those systems as well as having relative humidity distribution in thermal comfort range. The dehumidification effectiveness is found to be 63.7%, which is desirable and promising. The desiccant-based evaporative cooling system has a great potential to mitigate cooling demand of buildings not only in hot arid but also in temperate humid climates.