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This paper is the first two that report on the results of ASHRAE Research Project RP-1468. This paper presents an overview of the projectandthe three volumes of documentation included in the final report (Clayton et al. 2013). The purpose of the project was to produce reference models and guidelines for developing software to automate thermal model creation fromabuilding informationmodelintoabuilding energy simulation (BES) for energy simulations. This paper describes the methods of the research and presents highlights of the guidelines. The variety of uses for energy simulation in the building design process leads to a differentiation of several different kinds of thermal models that may be extracted from a BIM. A Series 2, Level 1 model that addresses whole-building energy use at schematic stages of design is developed into a set of guidelines. A recommendation is to use the centerlines of enclosure elements to determine areas of thermal surfaces. Various recommendations are made for resolving curved surfaces, shading elements, and site elements. The guidelines are supported by detailed sensitivity studies and analysis, presented in the final report (Clayton et al. 2013). The investigations led to identification of future work to improve energy simulation tools and BIM tools. [ABSTRACT FROM AUTHOR]

In commercial buildings with high glazing fractions, the transmission of solar radiation to perimeter spaces represents an important source of thermal influx, and is typically controlled with shading devices such as interior venetian blinds. The influence of interior blinds on cooling and heating loads is not straightforward or obvious: they may actually cause increases in cooling loads if they prevent solar influx from reaching room surfaces with thermal mass, while rapidly transferring the solar energy to the room air via convection. This paper presents the results of experiments conducted in an outdoor office-scale façade performance testing laboratory, designed to measure the effect of slat-type blinds on cooling energy. A number blind positions, slat angles, and slat colors were tested. A simulation model of the lab was developed in parallel to check the agreement with the blind modeling algorithms of EnergyPlus, by comparing daily energy consumption and the magnitude of peak cooling load. While an exterior blind was found to greatly reduce energy consumption and peak cooling load as compared to un-shaded glazing, all cases with indoor blinds showed minimal reductions in both energy consumption and magnitude of the peak. For both dark and light-colored interior blinds, the cases with slat angles at 45º resulted in higher energy consumption than the open slat cases, and the dark blind also exhibited a greater peak load. The model closely matched experimental results for bare glazing, but tended to overestimate the reduction in energy consumption and cooling load in the presence of blinds. In addition to the presentation of experimental results, this paper will present a critical a discussion of some key considerations for modeling a space with interior blinds. [ABSTRACT FROM AUTHOR]

Rapidly increasing requirements placed on utilities to reduce peak loads has led to utility customer incentives to shift peak demand to non-peak times or reduce peak loads when notified by the utility that the grid is close to capacity. This paper investigates methods used to reduce building demand during a fixed time window near a utilities on-peak period in response to short-term notification (a few hours advanced notice) through computer simulations using EnergyPlus. The work presented in this paper was performed under the ASHRAE research project, 1390-RP. Two building types (office and retail) were defined using two equally viable construction types (light and heavy mass). The four resulting building construction models, combining building types and constructions, were simulated in five selected cities which represent a diverse range of climate conditions. The control strategies investigated in the project include lighting power density reductions, global thermostat setpoint setback control, chilled water temperature reset, and supply air temperature adjustment. Results from computer modeling were analyzed. Demand reductions associated with changes in the thermal mass were insignificant compared to those achieved with control strategies. The lighting power density reduction is effective and easily implemented. Higher percent reductions in demand were achieved for the smaller buildings and medium retail building which used the packaged HVAC system type with global thermostat setpoint setback control. The peak demand reductions that are achievable when two or more control strategies are combined vary between 12% and 34% and are dependent on building and HVAC system types. [ABSTRACT FROM AUTHOR]

A run-around membrane energy exchanger (RAMEE) has been introduced in the literature as a novel energy recovery system that transfers heat and moisture between the ventilation and exhaust air. The RAMEE consists of two separate (supply and exhaust) flat-plate exchangers made of water-vapor permeable membranes and coupled with an aqueous salt solution. In this paper, the application of a RAMEE in an HVAC system is investigated. The paper discusses the dependency of RAMEE performance on ventilation air and salt solution flow rates and indoor and outdoor air conditions and describes how to control the RAMEE in different operating conditions (summer, winter, and part load). An artificial neural network (ANN) that is able to predict the optimal system performance was developed in previous research. The ANN results are used for TRNSYS computer simulation of the RAMEE system when operating in an office building in four different climates. The results show up to 43% heating energy saving in cold climates and up to 15% cooling energy saving in hot climates. Cost analysis proves the important role of pressure drop across the exchangers in life cycle cost and predicts a payback period ranging from 2 to 5 years for the RAMEE. [ABSTRACT FROM AUTHOR]

Energy modeling and optimization studies can facilitate the design of cost-effective, low-energy buildings. However, this process inevitably involves uncertainties such as predicting occupant behavior, future climate, and econometric parameters. As presently practiced, energy modelers typically do not quantify the implications of these unknowns into performance outcomes. This paper describes an energy modeling approach to quantify economic risk and better inform decision makers of the economic feasibility of a project. The proposed methodology suggests howeconomic uncertainty can be quantified within an optimization framework. This approach improves modeling outcomes by factoring in the effect of variability in assumptions and improves confidence in simulation results. The methodology is demonstrated using a net zero energy commercial office building case study located in London, ON, Canada. [ABSTRACT FROM AUTHOR]

This paper introduces and provides results from a rigorous, scientific testing methodology that allows pure building model calibration systems to be compared fairly to traditional output errors (e.g.,howwell does simulation output match utility bills?) as well as input-side errors (e.g., how well, variableby- variable, did the calibration capture the true building's description?). This system is then used to generate data for a correlation study of output and input error measures that validates CV(RMSE) and NMBE metrics put forth by ASHRAE Guideline 14 and suggests possible alternatives. [ABSTRACT FROM AUTHOR]

Outdoor airflow rate, building static pressure, supply air duct static pressure, and relief air plenum static pressure, as controlled variables, are maintained by modulating the speed of the supply and return fans and the position of the outdoor, recirculating, and relief air dampers in an air-handling unit (AHU). The three dampers are often interlinked completely or partially to match independent control inputs with the controlled variables. The traditional damper control has all three dampers interlinked with no control over the relief air plenum static pressure. Reverse relief airflow might occur as the outdoor air damper approaches the closed position. To prevent reverse airflow, one solution is to decouple the relief air damper and maintain positive static pressure at the relief air plenum. Two control methods are available based on the controlloopdesign. The first controlmethoduses the return fan speed to control the relief air plenum static pressure and the relief airdamperto control the building static pressure, and the second control method switches two control inputs. The purpose of this paper is to evaluate the controllability of the reverse relief airflow and building static pressure of these two control methods. The system performance is investigated through steady-state simulations on an AHU at different outdoor airflows using a nonlinear network solution. The simulation results show that both the control methods can well prevent reversere lief air flow. However, the first control method with a constant pressure setpoint may result in negative building static pressure at lower outdoor airflow ratio and either excessivelypositivebuildingstaticpressureorexcessivereturn fan power at higher outdoor airflow ratio. The second control method shows better control over the building static pressure control. A reset pressure scheme should be associated with the first control method when the relief damper is fully open. [ABSTRACT FROM AUTHOR]

Variable Refrigerant Flow (VRF) heat pumps are often regarded as energy efficient air-conditioning systems which offer electricity savings as well as reduction in peak electric demand while providing improved individual zone setpoint control. One of the key advantages of VRF systems is minimal duct losses which provide significant reduction in energy use and duct space. However, there is limited data available to show their actual performance in the field. Since VRF systems are increasingly gaining market share in the US, it is highly desirable to have more actual field performance data of these systems. An effort was made in this direction to monitor VRF system performance over an extended period of time in a US national lab test facility. Due to increasing demand by the energy modeling community, an empirical model to simulate VRF systems was implemented in the building simulation program EnergyPlus. This paper presents the comparison of energy consumption as measured in the national lab and as predicted by the program. For increased accuracy in the comparison, a customized weather file was created by using measured outdoor temperature and relative humidity at the test facility. Other inputs to the model included building construction, VRF system model based on lab measured performance, occupancy of the building, lighting/plug loads, and thermostat set-points etc. Infiltration model inputs were adjusted in the beginning to tune the computer model and then subsequent field measurements were compared to the simulation results. Differences between the computer model results and actual field measurements are discussed. The computer generated VRF performance closely resembled the field measurements. [ABSTRACT FROM AUTHOR]

Slinky ground heat exchangers are increasingly considered among more traditional ground heat exchanger configurations. Although studied for many years as a research topic, the increase in efficiency and reduction in building energy demands has increased the viability of these specialized heat exchangers, especially in cases where limited space is available for burying horizontal heat exchanger tubing. By formulating an accurate simulation model, the feasibility and efficiency of such heat exchangers in different climates and building configurations can be studied. In addition, it will serve as a powerful tool for design and energy analysis of the ground source heat pump (GSHP) systems. This paper describes the derivation of an analytic solution for modeling the thermal response of horizontal Slinky heat exchangers. The analytic results are presented in the form of temperature response factors. A computer module with fast algorithms is written to calculate temperature response factors of any specified Slinky ground heat exchanger. The factors then can be used as input for a buried pipe model to calculate hourly exit fluid temperature of the heat exchanger. Knowledge of exit fluid temperature is essential for simulation of a GSHP system. [ABSTRACT FROM AUTHOR]

This paper provides an overview of the variable refrigerant flow heat pump computer model included with the Department of Energy's EnergyPlus™ whole-building energy simulation software. The mathematical model for a variable refrigerant flow heat pump operating in cooling or heating mode, and a detailed model for the variable refrigerant flow direct-expansion (DX) cooling coil are described in detail. [ABSTRACT FROM AUTHOR]

Increasing loop chilled water return and supply temperature difference or delta-T is an effective way to improve the chilled water system efficiency and save chiller plant operating costs. In some chiller plants, the delta-T can be expected to fall to about one-half to two-thirds of design at low loads due to various causes, such as coil load, air entering and leaving temperatures, and chilled water supply temperature. Computational simulation is a useful and flexible tool to study cooling coil delta-T characteristics under various conditions. This paper simulated the cooling coil delta-T profiles with different geometric configurations and various waterside and airside conditions using an effectiveness-NTU model. The waterside heat convection coefficient was modeled with a combined correlation. The simulation results show that the existing waterside correlations generated significantly different delta-T profiles. With variant geometric configurations, the coil delta-T at full load may be higher, equal, or lower than that at part load. The complexity of cooling coil delta-T characteristics indicates that it is hard to make conclusions about the coil delta-T change with cooling loads. [ABSTRACT FROM AUTHOR]

The objective of this paper is to investigate the performance of two different types of Solar Domestic Hot Water (SDHW) systems , one with a gas boiler as the auxiliary heating source and the other with an electric tank as the auxiliary heating source, and to investigate the contributions of different components of the systems in lowering the annual energy demand and GHG emissions for producing 225 litres (59.4 gal) per day of domestic hot water. The systems are for the twin Archetype Houses located in Vaughan, Ontario, Canada. The annual energy consumption of the gas boiler and electric tank from the experimental analysis were to be 3718.7 kWh (12.69 MBtu) and 2778 kWh (9.48 MBtu), respectively. The TRNSYS models of the two systems were also created and validated with the experimental results. Using the TRNSYS models for a typical Canadian household in Toronto, Ontario, the annual energy consumption by the gas boiler and electric backup tank were concluded to be 3636.9 kWh (12.41 MBtu) and 2681.5 kWh (9.15 MBtu), respectively. The annual thermal energy output by the flat plate and evacuated tube solar thermal collectors were found to 2010.8 kWh (6.86 MBtu) and 1390.6 kWh (4.74 MBtu), respectively. The annual heat recovery by the Drain Water Heat recovery (DWHR) units were concluded to be 792.8 kWh (2.7 MBtu). [ABSTRACT FROM AUTHOR]