. Although considered obsolete, steam heating systems excels any other in simplicity and resilience and can match modern efficiency standards after thorough retrofit. Steam is the best heat transfer media , not water. 1 pound of condensed steam carries more heat than 25 pounds of hot water cooled in radiators by 40oF, no pumping is required. The flexibility offered by steam and steam generation from boilers will continue to keep the use of steam in our foreseeable future. Heat and power cogeneration (CHP) efficiency is up to 75% and 24/7 reliability, which makes it an attractive option for new large/tall buildings and campuse. According to 2010 reports in NYC the tradition of steam heat is so strong that even relatively new buildings have been found to be designed and built with steam heating systems. Most buildings above 50,000 square feet still use steam-based space heating. 72.9% of buildings have steam boilers fired by natural gas or fuel oil, while 10% rely on Con Edison’s district steam service. In other words, 81.9% of heating systems in large NYC buildings still use steam
With knowledgable maintanence superior efficiency and comfort can be achieved by steam heating systems even in very old buildings (1850th). US presidents and their spouses in White House and financial advisors in the US Treasury buildings would not accept anything but the best . Treasury building received a LEED Gold certification in 2011. Unfortunately, majoriy of steam heating systems are either neglected or recklessly modified or both.
Steam heating conversion into hot water heating (HWH) is considered the best approach for today. The take-away from the 2010 successful steam to HWH retrofit project on a twelve story building at 179 Henry str., NYC were summarized as follows: “Over the years, many of us in the New York City multifamily energy efficiency world have talked about how cool it would be to convert steam-heated buildings to hydronic heating. The problem is not one of will but one of money. Changing the boiler is not the big deal—it’s the heating distribution system that is the challenge. … Plenty of these conversions have been done in the last 20 years in buildings that were gut rehabs. These jobs did not always get the best boilers, or insulation in the walls, but they did get a more efficient heating distribution. The real challenge was to convert a building with steam heat, with tenants in place “. The project required boiler replacement, core drilling the concrete deck floors (12 in all), running and enclosing the new piping and the heating elements. Fuel savings were 33%.
Meanwhile the efficiency of a thoughtfully retrofitted steam heating system can match today’s standards:
● The 16-story 1893 Monadnock Building (Chicago) manages a top Energy Star score of 98 in spite of its age. … the brick skyscraper has cut electricity and gas consumption by about 33% by weather stripping, improved steam system automation, and the gradual installation of sensor controlled lighting
● The14-story historic Joseph Vance Building (Seattle) constructed in 1929 and retrofitted in 2006. For economic reasons, the project did not replace the existing steam heating system, but recalibrated it instead. In 2009, the U.S. Green Building Council (USGBC) awarded the Vance Building LEED for Existing Buildings (EB) Gold certification. The building also achieved an Energy Star rating of 98 (out of 100).
To resume:
● There are multiple cases of worn out steam heating system successfully replaced by HWH resulting in a savings ranging up to 40% (usually complementary to a building envelope and windows improvements)
● Many times old steam heating system demonstrated superior comfort and savings in a range of 30-50% thanks to knowledgeable maintenances and tune up
● It’s strange, in almost 100 years since the HWH introduction there was no single study of steam heating direct comparison to HWH. There is, though, accidental evidence of similar fuel usage in identical buildings with HWH and well-maintained steam heating.
Public fondness toward hydronic heating is constantly fueled by complaints about noise and low efficiency of the steam heating system which continued functioning even after decades of neglect and scarce maintenance. Dan Holohan, International Authority on Steam Heating and Hydronics discusses how to bring sustainability to older heating systems at GSMT meeting (video on the right). Energy efficiency achieved by nowledgable upgrades exceed the best result of connversion into HWH.
