James A. Love

Manual switching patterns in private offices

Switching behaviour is important in evaluating energy requirements of manual lighting control strategies and in understanding occupant reactions to daylight. Switching behaviour was observed and monitored in south- and north-facing private offices. The occupants appeared to fall into two different behaviour groups: (a) people who typically switched lights on for the duration of the working day, including unoccupied periods, and (b) those who used electric lighting only when daylight levels were low. Switching probability functions for two north-facing private offices were consistent with Hunts function for multi-occupant spaces.

The evolution of performance indicators for the evaluation of daylighting systems

The author reviews the development of performance indicators for the evaluation of daylighting systems. The comparative strengths and weaknesses of measures including the daylight factor, the glare index, the scalar illuminance, the illumination vector, and the ratio of the vertical illuminance to the horizontal illuminance are discussed.<<ETX>>

Signature analysis calibration of a school energy model using hourly data

An EnergyPlus model of a school with displacement ventilation and radiant slab thermal control was calibrated using signature analysis. Capacity to model these technologies is relatively recent in simulation software, and little has been published on calibration of energy models with these systems. The calibration of the as-built model required eleven adjustment iterations. Between iteration one and three; a group of weather-independent factors were modified. Between iterations four and eight; weather-dependent parameters were updated. The last three iterations addressed weather-independent electric demand parameters, for which hourly data were used. The calibrated model complied with the mean bias error (MBE) and coefficient of variation (CV) requirements of ASHRAE Standard 14. Hourly data were key to meeting the criteria for an adequate match between simulation estimates and the measured data. The MBE and CV of root-mean-squared error were 0.5% and 7% for electricity with daily data and 5% and 9% for gas with weekly data.

Trial application of ASHRAE 1051-RP: calibration method for building energy simulation

ASHRAE research project 1051-RP generated a method to improve the process of calibrating whole building energy simulation models based on monthly utility data. The approach, using manual generation of simulation model variations, was applied to a 12,000 m2 high-performance, dual energy, cold climate building. This led to 27 models that met the ASHRAE Guideline 14 monthly goodness-of-fit criteria for electricity, but had fit values for gas that were about 5–7 times the normalized mean bias error (NMBE) acceptance threshold. Five models met the criteria for natural gas and had acceptable coefficient of variation of the root-mean-square error for electricity, but NMBE was about 100% too high. Use of finer interval monitored data yielded a model with electrical NMBE about 60% above the acceptance threshold, and gas use about 200% above. Hourly analysis of the thermal energy demand on the plant showed wide discrepancies with the estimates on an hourly and half daily basis.

Applying quality control in building energy modelling: comparative simulation of a high performance building

Quality control is considered from the simulators perspective through comparative simulation of an ultra energy-efficient building with EE4-DOE2.1E and EnergyPlus. The University of Calgarys Leadership in Energy and Environmental Design Platinum Child Development Centre, with a 66% certified energy cost reduction rating, was the case study building. A Natural Resources Canada incentive program required use of EE4 interface with DOE2.1E simulation engine for energy modelling. As DOE2.1E lacks specific features to simulate advanced systems such as radiant cooling in the CDC, an EnergyPlus model was developed to further evaluate these features. The EE4-DOE2.1E model was used for quality control during development of the base EnergyPlus model and simulation results were compared. Advanced energy systems then added to the EnergyPlus model generated small difference in estimated total annual energy use. The comparative simulation process helped identify the main input errors in the draft EnergyPlus model. The comparative use of less complex simulation programs is recommended for quality control when producing more complex models.

Heating plant input–output efficiency in two cold-climate institutional buildings with condensing hot water boilers

Seasonal input–output efficiencies of two heating plants with condensing boilers in cold climate institutional buildings (3300 m2 school and 12,000 m2 university building) were evaluated. Plant efficiency remained about the same or declined with load, contrary to typical lab boiler ratings, which show efficiency increasing at lower loads. These results occurred when the boilers were operated with return water temperatures largely in the condensing range. Heating plant load was often 25% or less of the rated load of a single boiler, resulting in heating plant input–output efficiencies well below rated boiler efficiencies. Practical application : In-situ boiler plant input–output efficiencies can differ widely from manufacturers boiler efficiency curves. For applications such as simulation for energy-efficient design, effective decision-making depends on accurately estimating real-world performance.

Field performance of compact fluorescent systems

The performance and cost-effectiveness of compact fluorescent lighting systems were assessed for five building types. While several commonly used performance criteria were identified in advance, other performance attributes only became apparent during the study. Fixture and lamp costs are substantially higher than for incandescent systems, but are offset by much longer lamp life and greater efficacy. Comparative life-cycle cost estimates were developed. The balance between increased capital and decreased operating costs varies with electricity tariffs, labor costs for replacing burned-out lamps, and other factors. Compact fluorescents may be a desirable choice for other reasons such as reduced vulnerability to electricity price increases, reduced loads on emergency power systems, reduced temperatures in areas inadequately cooled by air conditioning systems, simplification of lamp inventories, reduced heat damage to exit sign enclosures, and prevention of inadvertent gross overlamping.<<ETX>>