Khee Poh Lam

Building energy and comfort management through occupant behaviour pattern detection based on a large-scale environmental sensor network

Detection of occupant presence has been used extensively in built environments for applications such as demand-controlled ventilation and security. However, the ability to discern the actual number of people in a room is beyond the scope of most current sensing techniques. To address this issue, a complex environmental sensor network is deployed in the Robert L. Preger Intelligent Workplace (IW) at Carnegie Mellon University. The results indicate that there are significant correlations between measured environmental conditions and occupancy status. It is shown that an average of 83% accuracy on the occupancy number detection was achieved by Gaussian Mixture Model based Hidden Markov Models during testing periods. To illustrate the consequent energy impact based on the occupant behaviour detection (i.e. number and duration of occupancy) in the space, an EnergyPlus model of the IW with an assumed standard variable air volume (VAV) system is created. Simulations are conducted to compare the energy consumption consequences between a prescribed occupancy schedule according to the ASHRAE 90.1 base case with the predicted occupancy behaviour. The results show that energy saving of 18.5% can be achieved in the IW while maintaining indoor thermal comfort.

EnergyPlus model-based predictive control within design–build–operate energy information modelling infrastructure

This study proposes a design–build–operate energy information modelling (DBO-EIM) infrastructure to allow users to deploy the design-stage building energy model for model predictive control (MPC) system in the building operation. A newly constructed office building is studied as a test bed. An EnergyPlus model-based predictive control (EPMPC) system is designed and simulated in the Matlab/Simulink environment within the DBO-EIM infrastructure. EPMPC aims at minimizing heating, ventilation, and air conditioning energy consumption while maintaining occupant thermal comfort. Compared to the baseline rule-based control system, EPMPC demonstrates a 28.9% energy reduction in one-week simulation in the heating season and 2.7% energy reduction in one-week simulation in the cooling season. The comfort constraint is met during more than 90% of the simulated hours. The study demonstrates one significant contribution of the DBO-EIM infrastructure that a design-stage EnergyPlus model can be integrated in an MPC system and the preliminary simulation results are satisfactory.

Education and environmental performance-based design: a Carnegie Mellon perspective

There are both negative and positive drivers for curricular change in architecture and architectural engineering departments to embrace more fully systems integration for building performance. On the negative side, failures in indoor air quality, spatial flexibility, acoustics and building integrity represent increasing challenges for designers, leading to costly litigation and remediation, and undermining the reputation of professionals. Heightened performance goals, including environmental sustainability goals, as well as emerging materials, components and system innovations require a greater level of expertise and collaboration between architect, engineers, building scientists and other disciplines. Advancing building performance quality and life cycle decision-making will require more integrated design processes. Least-first-cost decision-making and highpressure value engineering lead clients to decisions that compromise the quality of building projects, and the design community often lacks the relevant information to argue for life cycle quality.

Development of whole-building energy performance models as benchmarks for retrofit projects

This paper presents a systematic development process of whole-building energy models as performance benchmarks for retrofit projects. Statistical regression-based models and computational performance models are being used for retrofit projects in industry but these require existing utility data for calibration and validation. Furthermore, a common retrofit design question is the prioritization of choices for replacement of building components and systems yielding optimal energy performance for a given budget. Benchmarking techniques prescribed in current energy standards do not explicitly address such inquiry. Given these constraints and requirements, a benchmarking process is proposed, with categorization of input data, informational sources and relationships between the two. A schematic depiction of the process with data feed-ins from pertinent sources is given. Results indicate diversified use of data sources (for building envelope category) and extensive dependence on information flows external to current energy standards (for thermal zoning, occupancy, lights and equipment, operational schedules, etc.).

An online platform to automate LEED energy performance evaluation and submission process

Purpose – This study aims to develop a web-based tool – LEED Energy Performance Online Submission Tool (LEPOST) to reduce the submission cost of the leadership in energy and environmental design (LEED) application process and facilitate green building design. Lifecycle cost reduction is a major driver for designing green buildings. LEED rating system has been well recognised and widely used in the green building industry. However, certification cost incurred in time and money is often a deterrent for some projects. Design/methodology/approach – LEPOST automatically maps EnergyPlus and eQUEST energy simulation results to the LEED energy performance requirement submission templates using an extensible markup language (XML) data structure. It incorporates the Energy Star Target Finder online engine and current utility data to calculate points required to assess LEED Energy and Atmosphere Prerequisite 2 and Credit 1 automatically. Findings – A comparative case study is conducted using an office building proje...

Conformal adaptive hexahedral-dominant mesh generation for CFD simulation in architectural design applications

Mesh generation is a critical and probably the most manually intensive step in CFD simulations in the architectural domain. One essential feature is the large span of dimensional scales that is encountered in design, particularly if the model aims to simulate indoor and outdoor conditions concurrently, e.g., site at the magnitude of kilometers while building elements at the magnitude of centimeters. In addressing the challenge this paper presents an approach to generate adaptive hexahedral-dominate meshes for CFD simulations in sustainable architectural design applications. Uniform all-hexahedral meshes and adaptive hexahedral-dominant meshes are both generated for natural ventilation simulation of a proposed retrofit building in Philadelphia. Simulation results show that adaptive hexahedral-dominate meshes generate very similar results of air change rate in the space due to natural ventilation, compared to all-hexahedral meshes yet with up to 90% reduction in number of elements in the domain, hence improve computation efficiency.