IBPSA2011

The faulty operation of Heating Ventilation and Air Conditioning (HVAC) systems in commercial buildings can waste vast amounts of energy, cause unnecessary CO2 emissions and decrease occupant thermal comfort, reducing productivity.   We propose a new method of automating Fault Detection and Diagnosis (FDD), based on the modelling of operational faults in HVAC subsystems, using techniques from statistical machine learning and information theory.

This paper presents an analysis of whole-building performance modelling and simulation process of a low-energy single-family detached residence located in Northeast U.S. A total of six design alternatives are modelled with EnergyPlus to predict relative performance improvements associated with a diverse set of energy efficiency measures of both building envelope assemblies and unconventional HVAC systems with inclusion of on-site renewable energy technologies.

According to the Passivhaus Institute (PHI) the verification of a Passivhaus design must be carried out using the Passivhaus Planning Package (PHPP). A number of methods are now available for designers to access climatic data for use in PHPP design predictions. The original climate data provided for design and certification in the UK was derived from the reverse engineering of TRY data from dynamic simulations, for a limited number of locations.

Foundation Heat Exchangers (FHX) are a novel form of ground heat exchanger for residential applications and, by virtue of lower costs, could increase the up-take of efficient heat pump technology. This work has aimed to develop a new efficient model of such heat exchangers for system simulation. The recently developed Dynamic Thermal Network approach has been applied to formulate a model of the FHX that includes the basement, pipes and adjacent ground. This response factor approach allows complex three-dimensional geometries such as this to be represented.

The aim of this study is to identify the most effective strategies  to  improve  energy  performance  of  an  existing  typical  office  building  in  the  city  of  São Paulo/Brazil,  by  simulating  the  results  of  various  retrofit  interventions  in  EnergyPlus.  Appropriate lighting  levels  were  determined  and  the  potential  of  natural light was simulated. Various air conditioning systems were simulated, comparing the performance of VRF (variable refrigerant flow) split systems with and  the  use  of  economizer.

To predict the risk if mould growth, rot, deformations and cracks in wood, it is necessary to know the moisture levels in constructions and building components. This paper presents a theory and a two-dimensional PC-model based on the use of Kirchhoff potentials to calculate moisture flow in wood. Anisotropy is allowed for using different flow coefficients in the different directions, in both sapwood and heartwood. The theory also deals with the internal boundary between sapwood and heartwood, and the external boundary to the outer air.

The performance of night ventilation to cool buildings is highly sensitive to the convective surface heat flux. As a result, simulations in BES-models may largely over- or underestimate the real cooling potential of this technique. To assess this, a series of transient 2D CFD-simulations, including thermal mass in floor and ceiling, are made with variation on ACH, inlet temperature and inlet location. It is shown that the location of the inlet strongly influences the surface averaged convective surface heat transfer coefficients at the ceiling.

Within this paper an annual performance and daylight comfort analysis of building integrated photovoltaic (BIPV) is discussed, evaluated and compared to a common façade solution. The daylight comfort analysis includes annual illuminance, glare evaluations, and further daylight factor calculation. Secondly, dynamic thermal simulations are performed. The energy consumption of the luminaries is considered as part of the thermal internal gains.

To minimize the total power consumption of a central air conditioning system, optimal control variables are necessary. A simulation of a central air conditioning system and its components are modeled. Modeling of air conditioning equipment required optimization, and power consumption formulas are created from experimental data. Optimal control is applied to the actual central air conditioning systems. The effectiveness of optimization and accuracy of optimization calculations are verified. Prediction of air conditioning load is required for the optimization calculation.

The building sector is responsible for a major part of the energy consumption. A considerable reduction can be achieved by improving the operation of the buildings. A methodology to organize and standar-dize the ongoing commissioning of buildings was de-veloped. The method consists of 4 steps. An impor-tant criterion developing this method was cost-effec-tiveness. Therefore a top-down approach was chosen. A minimal dataset was defined which was measured at all demonstration buildings. In this paper different modeling approaches within the methodology are discussed.