In the 1980s, he was part of the planning and management teams for the construction of IDF bases in the Negev, transferred from Sinai following the peace agreement with Egypt.
In the mid-1980s, he came up with an innovative method of real estate development, whereby the end customer is in fact also the developer who purchases the plot and commissions construction services, thus cutting costs. This method later became known in Israel as purchasing groups.
Kalman went on to plan and execute dozens of purchasing groups projects for residential, office and commercial purposes, including BSR Towers 1 + 2 in Ramat Gan and Bnei Brak, Gibor Sport Tower in Ramat Gan, Manhattan Tower in Tzameret Park in Tel Aviv, Toyota Towers in Tel Aviv and more. In these projects, his role entailed finding a location, forming a group of consumers, and providing all the planning, management and supervision of construction and financial aspects, through to completion and occupancy, whilst coordinating and collaborating with all the stakeholders.
Over the years, he has developed, managed and erected dozens of projects in eastern Europe and the United States, and has won many awards. Nowadays he is the chairman of the Sufrin Group.