Decision models under uncertainty can be used as an alternative method for assessing the embodied energy and greenhouse gas missions of different heating equipment when detailed information is not available. The method can help in the estimation of life-cycle energy use of equipment by removing obstacles in the evaluation of embodied energy. The paper presents the estimation of environmental impacts from manufacturing a noncondensing, natural gas-fired hot-water boiler with a heat capacity of about 12 kW for residential applications, in the absence of accurate data about the materials used. Results from a case study found in the literature are used for the verification of the proposed method. The embodied energy in a hot-water boiler with the heat exchanger in aluminum, for instance, is about 20,000 MJ or about 30% of the total embodied energy of a house and in the case of stainless steel, it is about 3,000 MJ or about 5%.