A small specialized workshop of floor area 200 m² is to be lit to an illuminance of approximately 1000 lux by high-frequency fluorescent tubes of efficacy 80 lm/W with a circuit load of 62 W. Water-cooled luminaires are installed with the water flowing in parallel through each luminaire. The heated water is pumped through a heat exchanger which acts as the heat sink for a heat pump used to heat air for building heating purposes. Using the data below, calculate (i) the number of luminaires required; (ii) the total mass flow rate of water required; and (iii) the rate of energy input to the air for building heating. (40 luminaires, 0.0346 kg/s, 2.6 kJ/s)

Data: Operating temperature of fluorescent tube, 30C temperature of water at entry to luminaire, 10C minimum temperature difference required for heat transfer to the water, 8 K (in order to have an effective heat exchange; that is, the water exit temperature is kept below 30 at 30 - 8 = 22C in this case.)