Steam Heating Conundrum of High-Rise Buildings

*Igor Zhadanovsky*

### **Abstract**

Steam/vacuum heating systems are employed in thousands of old tall buildings and even relatively new ones. Although considered obsolete, these systems excels any other in simplicity and resilience and can match modern efficiency standards after thorough retrofit. Efficient and simple, the NextGen vacuum heating is suggested for existing steam heating systems retrofit and for new installations that use modern technologies and materials.

**Keywords:** high-rise, vacuum heating, steam, retrofit, steam heating

#### **1. Introduction**

Till 1930 all skyscrapers were built in North America/US (191/188) [1]. Typical office towers and high-rise residential and hotel buildings were not higher than 150 meters [2]. They were heated by steam systems, − the most convenient way to deliver heat to upper floors. Reliable hot water circulators were introduced in 1929, and quickly gained popularity because the cost of heating system installation was reduced drastically. It's a reason why in this article most of the data on steam heated high rise buildings are of US/NYC origin, but proposed solution can be applicable for future high-rise construction worldwide.

In Europe a record number of skyscrapers were completed in the first decade of the 21st century and it appears that this record might be surpassed in the next. Although Europe constructed first supertall skyscrapers, European buildings generally do not exceed 250 meters. Today, the majority of European skyscrapers are office buildings; although in the 21st century there has been an increasingly significant tendency to equalize the quantity of residential and office buildings [2]. The skyscrapers are changing the skylines of high populated cities - **Figure 1** (NYC) and **Figure 2** (Chicago) are good examples.

The elephant swept under the rug – steam heating in high-rise buildings. Swept under the rug is an idiom used for something that has been hidden from the view of others due to embarrassment … You have all the dirt, but too lazy or lacking in time to find something to pick it up, so you lift the corner of the rug and sweep it under.

Today's consensus on HVAC with the highest efficiency for tall buildings is a "ground source heat pump (HP) combined with hydronic piping, and smaller water source heat pumps for each building zone. One kilogram of water can carry over four

#### *Recent Updates in HVAC Systems*

**Figure 1.** *The downtown New York City skyline.*

**Figure 2.** *Skyscrapers in Chicago.*

times more heat than one kilogram of air, while being pumpable and using over 800 times less space. This makes water an ideal heat transfer medium for tall construction" [3].

Apparently, enthusiasm for heat pumps obscures the fact that the best heat transfer media is steam, not water. 1 pound of condensed steam carries more heat than 25 pounds of hot water cooled in radiators by 40°F, no pumping is required. Additionally, in tall buildings every 20th floor of precious space is lost for hot water pumps, which is a huge budget sacrifice. The choice of a HP is also questionable because HP efficiency drops sharply at low outside temperatures, meaning the backup system is required when heating is needed the most. Backup system is either an electrical resistance or Power Plant. HP requires 24/7/365 electricity which is produced from oil or gas at maximum theoretical efficiency of 35%. To circumvent such losses, free "green" electricity from solar and wind is asserted as todays "holy grail" to power HP.

In real life, the iconic "green" program in Germany upsurge electricity cost and was finally exposed as a catastrophic failure [4]. Still the public is mesmerized by futuristic ideas. "The growth of wind and solar power offer the opportunity to reduce the cost of electricity, and certainly reduce the amount of emissions. However, this only accounts for about 3% of the total U.S. energy use or about 9% of electric generation energy. In addition, electric generation from wind is often at the wrong time of the day. While there are many ways of solving these problems, solutions will not be easy or inexpensive. Even if there is a conversion to more electric generation from wind and solar, steam will still be the best means of converting electricity to a useful energy source for heating and process work. It simply means that the boiler will use

*Steam Heating Conundrum of High-Rise Buildings DOI: http://dx.doi.org/10.5772/intechopen.108107*

electricity for its energy source. The flexibility offered by steam and steam generation from boilers will continue to keep the use of steam in our foreseeable future" [5]. 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 campuses.

Pragmatism prevailed over wishful thinking, − 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" [6]. "28 newly constructed properties, totaling over 7.5 M SF (1SF = 0.0929 M2) of building area, installed some form of steam heat between 2000 and 2010. Most buildings above 50,000 SF 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 [7]. The propensity/partiality toward steam heating in large buildings is typical of big cities in the US and in Europe as well [8].

### **2. Solutions already tested, found inefficient but still employed**

The inborn drawback of steam heating is uneven heat distribution. Steam of 2 psi pressure (safety limit) has to push air through multiple air vents every heating cycle in order to get simultaneously into each radiator hundreds feet away. That's why ¨Dead Men¨ meticulously equilibrate boiler capacity, pipes and radiators sizes, pressure drop and heat load for each installation. As of today, efficiency and comfort in the majority of these systems is ruined due to poor maintenance and reckless modifications. It's a reason why steam heated buildings are typically pictured with open windows. Methods to overcome the problem are as follows:

*Balancing* using air vents [9, 10], orifices [11] and Temperature Regulating Valve (TRV) [12] is time, money and labor intense, resulted a modest 10–14% fuel savings or no savings at all, but still widely employed to supplement building envelope and lighting upgrade.

*"Smart' radiator cover"* [13] addresses room overheating rather than the whole heat distribution problem, another disadvantage is switching from radiation to convection heating by air which causes a significant decrease in efficiency and comfort.

*Variable refrigerant flow (VRF)* is today's popular type of HP in which one outdoor unit can be connected to multiple indoor units. Each indoor unit is individually controllable by its user and a variety of unit styles can be mixed and matched to suit individual tenant requirements (e.g. high wall units, cassettes, and ducted units). Recent study concluded that buildings most suitable for MSHP (Multi Split Heat Pump) retrofits are those with high-cost heating fuel such as liquefied petroleum gas (propane), fuel oil and, especially, electric resistance. Buildings with natural gas service are less suitable. Converting from electric resistance to MSHPs saves approximately 30% of annualized energy- related. Converting from oil saved about 4%. Converting from natural gas would cost about 30% more. In the Boston climate, converting from electric resistance to MSHPs is projected to save approximately 50% of annualized energy-related costs. Converting from oil saves about 3%. Converting from natural gas would cost 24% more. VRFs are suitable as primary heat sources in new well insulated construction" [14]. In old buildings (and most steam heated buildings are 50+ years old) a backup heating system is a must to have.
