New engineering design means and methods are needed to enable and speed the adoption of low carbon retrofit technologies. Decarbonization requires adapting distribution designed for legacy thermal supply— whether steam, hot water, forced air, or unitary— to systems with a carbon-free heat. New design strategies are emerging which can also alleviate space constraints issues, provide peak thermal capacity, optimize operational efficiencies, utilize waste heat, and reduce the need for oversized electrified thermal energy systems creating retrofit cost compression. Interventions must be minimally intrusive to tenants and scalable for portfolio owners, functioning continuously in a phased decarbonization plan. A variety of technological solutions demonstrate promise: hydronic distribution; exterior/envelope integration; reusing/modifying existing thermal, sanitary, fire suppression, and other distribution systems; and integration with thermal storage. |