NBSLD, the computer program for heating and cooling loads in buildings

In the late 1960s, under the sponsorship of the Department of Housing and Urban Development, Tamami Kusuda began to develop a computer program to help architects and engineers predict the thermal performance of a building. Important enough at the time, this work was to balloon in significance in the context of the energy shortages and rapidly escalating energy prices of the 1970s. The computer program was named the National Bureau of Standards Load Determination (NBSLD) program [1,2]. It combined algorithms for transient conduction in the building structure, solar heat gains and radiant transfer, and convection between building surfaces and the room air to allow the prediction of temperatures and heating and cooling loads under dynamic conditions. Moreover, the algorithms employed in NBSLD were adopted by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) as a recommended procedure for computerized energy calculations. They were presented to the Society in a special publication [3] which was sold for many years.