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

seals installed, so it is believed that updated natural gas utility data, which were not available,would place Houghton Hall closer to the ‗Good Practice‘ side of the scale.In evaluating the indoor environment, the carbon dioxide levels that were measured throughoutthe year were found to vary by season. However, the levels within the building were not close tothe levels at which there would be cause for concern or occupant dissatisfaction. Even during thewinter months, the differential between the outside level and the interior level taken at the secondfloor was 360 ppm with the building fully occupied. During the summer months, there isdefinitely adequate airflow to meet indoor air quality levels without any potential health issues.Table 17. Comparison of ECG 019 Benchmark, Mechanically Ventilated (MV) and NaturallyVentilated (NV) BuildingsMV Std. MV GP NV Std NV GP UFAD MV* Luton NV*Total Energy Usage kWh/m 2 404 225 236 133 318 216Total Natural Gas kWh/m 2 178 97 151 79 162 140Total Electricity kWh/m 2 226 128 85 54 156 76Lighting & Office kWh/m 2 85 50 65 42 55 51Refrigeration kWh/m 2 31 14 0 0 29 0Fans & Controls kWh/m 2 60 30 8 4 50 5* Data from Experimental MeasurementsThe importance of incorporating natural ventilation into building design is further emphasized,including the benefit in energy conservation, through comparisons made between Houghton Hall(Luton) and another similarly laid-out office building located in Sunbury, within relatively closeproximity. The main difference between the two buildings was the method of ventilation. Bothbuildings were located in office parks, and were three stories in height with an open office floorplan and central atrium. The mechanically ventilated building employed rooftop units andchillers to introduce and condition outside air for the building, rather than incorporating naturalventilation in the design. It had an all-glass façade but was a completely sealed building, with anunder-floor air distribution (UFAD) mechanical system controlled by a building energymanagement system. This mechanically ventilated building was monitored in similar detail to theprototype building in Luton, including electrical energy detailed sub-metering, temperaturedistribution, and ventilation performance. Table 17 summarizes the range for both themechanically ventilated office building and the naturally ventilated one, with the results for thetwo buildings.The naturally ventilated prototype building used 13.6 percent less natural gas usage. Of moresignificance was the reduction of over 50 percent in electric energy usage per floor area. Themechanically ventilated building was an all-glass façade, with more surface area which maycontribute to the higher natural gas usage. Both buildings were ‗un-conditioned‘ on the weekendsand both incorporated energy saving features on both lighting fixtures and office equipment. Theoverall energy consumption per floor area for lighting and office equipment is quite similar forthe two buildings. However, the energy required for mechanical cooling or the refrigerationcategory makes a substantial difference. There is a substantial amount of additional energy usagerequired for using refrigeration, in the form of a chiller, within the office building in thetemperate climate of the UK. By relying on the environment for not only cooling, but also air68