For the past few years, nuclear utilities have been interested in the calculation of transient room temperatures at various station locations following loss of heating/ventilating/air conditioning and/or following station blackout. Transient room temperature analyses invariably involve the use of computer programs utilizing various finite difference schemes. A manual solution method is proposed for room heatup transients, thereby reducing the engineering time spent to obtain the results from tens (occasionally hundreds) of hours to a few hours in many cases.