Methodology for the Evaluation of Natural Ventilation in ... - Cham

environmental conditions are examined, then the consumption by heating and/or coolingequipment can be determined. The degree-day data are readily available online from weatherwebsites.A more detailed method of determining the energy performance of a building includes submeteringmajor energy using systems within a particular building. This method provides detailedinformation on the operation and consumption patterns of a building. Though requiring moreinvestment in terms of time and equipment, understanding the energy usage for a specific systemand for specific zones on an hourly or quarter-hourly basis can provide the more detailed dataneeded to improve the performance of a building. Common systems to monitor, as applicable,include the plug loads, lighting loads, chiller or other cooling system, air handling units,miscellaneous pumps, exhaust systems, and exterior lighting. These data can then be used tocompare a building‘s performance to benchmark data.2.4.4 Long Term MonitoringRecording data over a twelve month period of time or longer can provide important insights intothe overall operation of a building. The monitoring should be designed so that enough data topaint an accurate picture of the building performance are obtained. Fifteen-minute intervals areoften used as they provide sufficient information for the partial hourly operation. Additionally,with commercial buildings, the thermal time response, occupancy patterns, and energy usage areslow enough to not require a shorter time interval. Long term monitoring includes energy usage,both by overall consumption and detailed by sub-system, internal conditions, includingtemperature and relative humidity, and external conditions.Even in temperate climates, the external environment can impact the performance of a building.As a building goes through the seasons, the internal conditions and sometimes the schedule ofoccupants and equipment change. To best evaluate the performance of a given building,continuous monitoring for an entire year, through heating, cooling, and mild shoulder monthsprovides the widest variety and most detailed data for analysis. The ability to record the outdoorconditions helps greatly in the analysis of the building. This includes the outdoor temperature, aswell as the solar gain and wind.With naturally ventilated buildings that often do not have cooling systems installed at all (orprovisions to install them), data describing the summer conditions, and sometimes the shouldermonths at the end of spring and beginning of fall, are important to ensure that there is a goodinternal environment for occupants. An understanding of the indoor environment can beascertained by measuring internal temperatures throughout a building., During the winter monthsthese buildings rely on infiltration to provide the required outside air since there is no forced airsystem in naturally ventilated buildings. This reliance can cause drafts and occupant discomfortif the infiltration is not purpose-provided and well controlled. One method for long-termevaluation of infiltration and ventilation is the use of carbon dioxide sensors. The interior levelscan then be measured throughout the year, compared with the outside levels, and the airexchange rate of the building determined based on the number of occupants by measuring thelevels of carbon dioxide in the external environment to provide a baseline.38