Steam heating is popular in New York City buildings for a very simple reason: steam rises on its own, which made it a practical means of providing heat before electric water pumps became widely available. In new construction, hot water systems with hydronic piping are by far the best choice, both in terms of efficiency and environmental impact.
The main reasons why many steam-based systems are not replaced are the cost of upgrading and the resulting business disruption. However, there are many situations that favor such updating and property management companies must take them into consideration. This article will describe some cases where there are extra reasons to consider an upgrade from steam to hot water.
1) Buildings without district steam service
Steam is cost-effective for high-rise buildings in parts of New York City where Con Edison provides district steam service, since property owners are not responsible for generating the steam they use. Con Edison benefits from economies of scale and as a result, buying steam from them is cheaper than producing it on site. Another detail is that Con Edison has a legally binding renewable generation target of 50% by 2030, which means that its steam is produced using methods with a lower environmental impact than those used in buildings. While buildings use boilers powered by heating oil or natural gas, Con Edison produces much of its steam using waste heat from power plants (cogeneration).
However, buildings that operate their own steam boiler should definitely consider upgrading to hot water. For a given heating load, a steam-based system will always consume more fuel than an equivalent hydronic system. Of course, there are exceptions where steam cannot be completely displaced: the healthcare sector often uses steam to sterilize equipment and humidify air, for example.
Of all New York City buildings above 50,000 ft2 , nearly 82% use steam heating, but only 10% have access to Con Edison district steam service. Everyone else relies on their own boilers.
2) Buildings with oil-fired steam boiler
Heating oil has a much greater environmental impact than natural gas. Additionally, petroleum-based systems are more expensive to operate and more difficult to manage than gas systems: while a gas boiler receives a constant supply from Con Edison, an oil boiler requires scheduled deliveries.
Con Edison offers great discounts when upgrading a heating system from oil to natural gas, so a fuel conversion project is also a great opportunity to implement hydronic piping. Radiators can often be adapted to operate with hot water rather than steam, and the required pumping system can use NEMA premium efficiency motors to minimize energy consumption.
3) Buildings where major renovation is planned
Many homeowners continue to use steam to avoid the hassle of a system conversion, even though they know hot water is the most economical option. However, if a major building renovation is planned, there will be disruption anyway, so it represents a great opportunity to convert heating systems from steam to hot water. However, reviewing New York codes is very important, as many new requirements will apply if the building has not been renovated for a long time.
A major renovation also offers a unique opportunity to make the building as efficient as possible, with upgrades that achieve synergy. For example, if the building envelope is improved to improve insulation and air tightness, the new heating system can have greater efficiency along with a reduced rated capacity. An older building with poor insulation, air leaks and an oil-fired steam boiler consumes much more energy and produces much more emissions than another building of the same size with a high-performance envelope, an efficient gas boiler and hydronic distribution piping of heat.
Conclusion
For most buildings, hot water distribution is better than steam heating, both from an economic and environmental point of view. The Urban Green Council has determined that steam-to-hot water conversion represents one of the largest areas of opportunity to reduce New York City's energy consumption and environmental footprint.
Homeowners considering a hydronic heat distribution upgrade can contact a qualified engineering firm to receive a professional assessment and an integrated solution, rather than a simple equipment upgrade performed in isolation from other building systems.
