A proposed new school building comprises 20 identical classrooms that are each 4m wide, 15m deep, and 3m high. Internal heat gains are 3kW. Windows are located in a single façade. Each classroom has a very high thermal efficiency and contains 30 children and staff who occupy it between 0900-1500hrs. Classrooms are vacated each day during a 1-hour lunch break and two 20-minute breaks, and then vacated for the duration of the summer vacation from July 20th to September 1st inclusive.
(a) Calculate the air change rate for each classroom and for the whole school if the required airflow rate is 5l/s per person.
The school manager states that their new building must be air conditioned. To help them understand the potential consequences of this decision and to advise them on the consequences, discuss the following and provide sketches if appropriate:
(b) What is an air conditioning system?
(c) The systems and components that must be installed.
(d) The ramifications for occupant thermal comfort.
(e) Costs and carbon emissions.
The school manager is interested in the viability of a natural ventilation (NV) strategy for these thermally efficient classrooms but is concerned about overheating in the summer. To help them understand the potential consequences of this decision and to advise them on the consequences, discuss the following and provide sketches if appropriate:
(f) A possible NV strategy including any architectural changes required. [15]
(g) Thermal comfort issues by considering an appropriate comfort model, heat gains, orientation, and construction material properties.