7 research outputs found
Building Space Thermal Control Model Responding to Sharp Changes in Outdoor Temperature
As computing and data-driven technologies have improved, the precision of the building thermal control models has been gradually improved, but the use of energy resources to operate them has been also increased. It is imperative to investigate the optimized point of energy use and human comfort for their thermal control strategies. The aim of this research is to find an energy-efficient thermal control model to maintain the constancy of thermal comfort and suppress the increase of energy use in association with precise environmental controls. Based on a cooling and heating air supply model in a simplified building model, a comprehensive energy use pattern is confirmed by adding an adaptive control model that allows indoor thermal comfort to be maintained at a setting level. The adaptive control model utilizing the artificial neural network and the adjustment process of initial settings is proposed to examine its performance in controlling the amount of thermal supply air and its temperature. For the clear comparison between a baseline model and a proposed model, the statistical indices of each thermal dissatisfaction value and the weekly heating energy use are utilized. The results of this research show that the thermal dissatisfaction fluctuation is alleviated by about 22.0~41.0% and the energy efficiency is improved by about 5.1%, respectively. The results provide the effectiveness of the proposed model which can improve both the energy use and thermal comfort in a building space. This advantage can help old thermal systems to improve their usability without replacing any major components
Energy assessment in early architectural design stages : framework and validation methodology for architect-friendly computacional energy assessment
Todayâs buildings are responsible for about 40% of the global energy demand. To reduce energy consumption by using Energy Assessment (EA) methods, the Early Architectural Design Stages (EADS) are especially suitable to implement the best cost-benefit measures. To integrate EA into EADS, two main challenges must be simultaneously tackled: (a) the architect-(un)friendliness of computational models and (b) the resultsâ reliability. To accomplish both goals a Framework for Energy Assessment Tools in Early Architectural Design Stages (FORwArDS) and a validation methodology, Relative Validation (RV), is presented. FORwArDS feature three components: Input Model, Assessment Model, and Output Model, but focuses on the creation of a Simplified Input Model (SIM) throughout parameters reduction, the creation of alternative values for the chosen parameters and exemplary mathematical and geometrical simplification steps. In the case study, a SIM is created according to the exemplary simplification rules described in FORwArDS, springing from a detailed project model; a validation procedure follows the proposed methodology. The results are presented, analyzed and conclusions are drawn regarding the frameworkâs and validation methodologyâs contributions to the improvement of the EADS. The frameworkâs open structure and the applicability of the validation methodology to any simulation contribute to the discussion about the integration problems of energy assessment in EADS and present useful tools for the creation and test of model simplification methodologies and EA for architects during EADS.EdifĂcios sĂŁo responsĂĄveis por cerca de 40% da demanda global de energia. Para reduzir este consumo utilizando mĂ©todos de avaliação de energia (Energy Assessment â EA), as primeiras etapas de projeto arquitetĂŽnico (Early Architectural Design Stages â EADS) sĂŁo especialmente adequadas para implementar medidas eficientes com a melhor relação custo-benefĂcio. Para integrar a EA na EADS, dois desafios principais devem ser abordados simultaneamente: (a) a (nĂŁo-)amigabilidade para arquitetos dos modelos computacionais e (b) a confiabilidade dos resultados. Para realizar ambos os objetivos, Ă© apresentado neste trabalho um ambiente para o desenvolvimento de ferramentas de aferição de energia em EADS (Framework for Energy Assessment Tools in Early Architectural Design Stages âFORwArDS) e uma metodologia de validação, a validação relativa (Relative Validation â RV). FORwArDS possui trĂȘs componentes: o modelo de entrada, o modelo de avaliação e o modelo de saĂda, mas o trabalho concentra-se na criação de um modelo de entrada simplificado (Simplified Input Model â SIM) atravĂ©s da redução de parĂąmetros, da criação de valores alternativos para os parĂąmetros escolhidos e, por fim, passos de simplificação matemĂĄtica e geomĂ©trica. A estrutura aberta do ambiente permite uma ampla variedade de aplicaçÔes em pesquisa, prĂĄtica e educação. A metodologia de validação proposta baseia-se no conceito de que a contextualização dos resultados obtidos representa a mais importante contribuição para a orientação de projeto no EADS. Este trabalho confronta pares de resultados, representando a mudança de projetos arquitetĂŽnicos similares originados em dois modelos de entrada diferentes, visando avaliar a precisĂŁo de seus correspondentes. No estudo de caso, um SIM, proveniente de um modelo de projeto detalhado, Ă© criado de acordo com as regras de simplificação descritas no FORwARrDS. Os resultados sĂŁo apresentados e analisados permitindo conclusĂ”es sobre as principais contribuiçÔes deste trabalho. O trabalho apresenta uma ferramenta Ăștil para o desenvolvimento de metodologias de simplificação de modelos e EA para arquitetos durante EADS
An investigation into the energy and control implications of adaptive comfort in a modern office building
PhD ThesisAn investigation into the potentials of adaptive comfort in an office
building is carried out using fine grained primary data and computer
modelling. A comprehensive literature review and background study into
energy and comfort aspects of building management provides the
backdrop against which a target building is subjected to energy and
comfort audit, virtual simulation and impact assessment of adaptive
comfort standard (BS EN 15251: 2007). Building fabric design is also
brought into focus by examining 2006 and 2010 Approved Document
part L potentials against Passive House design. This is to reflect the
general direction of regulatory development which tends toward zero
carbon design by the end of this decade. In finishing a study of modern
controls in buildings is carried out to assess the strongest contenders that
next generation heating, ventilation and air-conditioning technologies
will come to rely on in future buildings.
An actual target building constitutes the vehicle for the work described
above. A virtual model of this building was calibrated against an
extensive set of actual data using version control method. The results
were improved to surpass ASHRAE Guide 14. A set of different scenarios
were constructed to account for improved fabric design as well as
historical weather files and future weather predictions. These scenarios
enabled a comparative study to investigate the effect of BS EN
15251:2007 when compared to conventional space controls.
The main finding is that modern commercial buildings built to the latest
UK statutory regulations can achieve considerable carbon savings
through adaptive comfort standard. However these savings are only
modestly improved if fabric design is enhanced to passive house levels.
Adaptive comfort can also be readily deployed using current web-enabled
control applications. However an actual field study is necessary to
provide invaluable insight into occupantsâ acceptance of this standard
since winter-time space temperature results derived from BS EN
15251:2007 constitute a notable departure from CIBSE environmental
guidelines
A Study of Impact of Thermal Model Resolution and Zone Set Point Profiles on Peak Heating Load and its Calculation
This thesis presents an experimental and theoretical study of the dynamic
response of convectively heated buildings and their respective space heating peak
demands for different room temperature set point profiles and thermal mass levels,
with a focus on the impact of thermal model resolution on the peak demand
calculation.
Experiments were conducted at two identical and highly instrumented houses.
One house is modified with different
oor coverings, while the other is kept unchanged
and used for reference. Through experimentation and simulation, peak
power (due to space heating) reduction strategies are investigated.
Twelve equivalent RC thermal network models of varying model resolution
are developed for a north zone of the houses. Modelling approximations including
linearization of the heat transfer, spatial and/or temporal discretization and approximations
for reduction in model complexity are implemented into the models
and their effects are investigated. The focus is on simple and physically meaningful
building thermal models suited for model-based control.
The models are used to study the impact of set point ramping lengths and
\near-optimal" transition curves between two temperatures on peak demand reductions
for a very cold day. Alterations to walls and ceilings in the models
were done to hypothetically modify their properties in the zone and the effects
in combination with ramping profiles were analyzed. This work can inform the
development of new building materials.
A commercial building is also considered and two low order RC thermal network
are compared. The first model excludes the mass of the interior partitions,
while the second model incorporates them. An advantage of the model with interior
partitions is it can be used for retrofit studies
Studies on SI engine simulation and air/fuel ratio control systems design
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.More stringent Euro 6 and LEV III emission standards will immediately begin execution on 2014 and 2015 respectively. Accurate air/fuel ratio control can effectively reduce vehicle emission. The simulation of engine dynamic system is a very powerful method for developing and analysing engine and engine controller. Currently, most engine air/fuel ratio control used look-up table combined with proportional and integral (PI) control and this is not robust to system uncertainty and time varying effects. This thesis first develops a simulation package for a port injection spark-ignition engine and this package include engine dynamics, vehicle dynamics as well as driving cycle selection module. The simulations results are very close to the data obtained from laboratory experiments. New controllers have been proposed to control air/fuel ratio in spark ignition engines to maximize the fuel economy while minimizing exhaust emissions. The PID control and fuzzy control methods have been combined into a fuzzy PID control and the effectiveness of this new controller has been demonstrated by simulation tests. A new neural network based predictive control is then designed for further performance improvements. It is based on the combination of inverse control and predictive control methods. The network is trained offline in which the control output is modified to compensate control errors. The simulation evaluations have shown that the new neural controller can greatly improve control air/fuel ratio performance. The test also revealed that the improved AFR control performance can effectively restrict engine harmful emissions into atmosphere, these reduce emissions are important to satisfy more stringent emission standards