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

movement, Houghton Hall has much less energy consumption for both refrigeration and fanenergy usage. Overall the mechanically ventilated system used 354.5 kWh/m 2 compared to thenaturally ventilated building with 216.1 kWh/m 2 .A factor that is often of some concern with buildings that do not have active cooling systemsinstalled is temperature conditions within the occupied space, and the amount of variation withinthe occupied space. In the prototype building, there was temperature variation throughout theoccupied hours, with personal fans used to provide additional breezes on particularly warm days.The vertical temperature within an occupied space could vary by as much as 3ºC, with furthervariation from floor to floor. On the other hand, in the building that had mechanical ventilation,the temperature never varied by more than 2ºC.3.8 Challenges with Monitoring a Naturally Ventilated BuildingFrom the analysis of Houghton Hall, there were several lessons learned, not only themethodology in assessing a naturally ventilated building, but also the thermal, ventilation, andenergy performance of this type of building. It was determined that this naturally ventilatedbuilding generally met comfort conditions in the temperate climate of the UK, even in theextreme heat of 2003. The design characteristics incorporated into the building did seem to helpin tempering the internal temperature, but more can be done to take further advantage of featuressuch as thermal mass. There are strategies that are recommended for the operation of the fans inthe atrium stacks. Running the fans at nighttime during the summer season would help to precoolthe building further, enhancing the affect of the thermal mass. Having the fans operatingwhen it is warm outside actually draws in the hot outside air, and reduces the effectiveness of thethermal mass.Though infiltration is welcome in the summer months, there was some concern with possibleleakage issues in wintertime that cause the boilers to engage. Since the windows are closedduring the winter months, but outside air is still required, the only outside air seemed to enter thebuilding when the main front door was open, allowing gusts of cold outside air to enter thebuilding.Occupants were surveyed in the spring, fall, and summer periods to evaluate comfort, using a 7point scale. The goal of the surveys was to determine perceptions of comfort, indoor air quality,and personal control in the building. In general, the occupants were warm during the summer,neutral during the fall, and slightly cool during the spring (Walker 2004). The summer surveyswere taken just after the heat wave in August 2003, and may be slightly skewed. The occupantsdid alter their perception of thermal comfort over the period of the day, corresponding withincreased internal temperatures.It was shown that Houghton Hall compared relatively well to open floor plan naturally ventilatedbuildings when compared to ECG019. When comparing this commercial office building to asimilar mechanically ventilated office building, the energy consumption was significantly lowerprimarily due to the lack of mechanical cooling, or refrigeration equipment. This can have adistinct impact on energy consumption and the resulting carbon dioxide emissions.Contrary to many mechanically ventilated buildings within a prescribed temperature range, therewas no building management system to control the internal temperature of the naturally69