A novel TiO2-coated foam-nickel photocatalytic oxidation (PCO) air purifier was designed for applying to heating, ventilating and air-conditioning (HVAC) systems. The face velocity of foam nickels was reduced by increasing skillfully windward area so that the problems of quite low removal efficiency and high pressure loss at high flow velocities were solved. A method to evaluate energy consumption of PCO air purifiers was presented for helping the design and the application of PCO air purifiers. The performances of the purifier were analyzed, including resistance. removal efficiency, reaction rate, and energy consumption. The results showed that increasing windward area is an effective method to reduce resistance and improve purification performance. The resistance of the purifier was less than 21 Pa when the flow velocity was less than 2 m/s. An additional driving apparatus will not be needed when the purifier is applied to a HVAC system. The flow velocity with the maximum reaction rate was 0.66 m/s, and it can be adjusted by changing windward area. The energy consumption should be reduced further when the purifier is used in summer in Shanghai. Some improvement measures were given to decrease the energy consumption. (c) 2009 Elsevier B.V. All rights reserved.