The Re-Greening of Commercial Buildings

 

Many commercial buildings constructed before the 1960s were heated hydronically, that is: with hot water or steam heat. Forced air systems moved in vigorously during the next several decades. Though, lately – with the rise of ultra-high efficiency hydronic systems and the nouveau popularity of in-floor radiant heat – hydronic systems began a forceful comeback in the 90s.

 

Current economic woes have yanked the growth curve downward, so most movement in the hydronics industry has returned to replacement and retrofit work. Even though banks have tightened the purse strings on funding for commercial work, there’s still a fair amount of “re-green” retrofit work happening now inside commercial buildings nationwide, thanks in part to Federal and state energy improvement incentives. 

 

The three primary areas where system performance and energy improvement changes are being made are these: boiler replacements, pump system retrofits, and piping enhancements, improving flow, system efficiency and offering comfort and convenience in a ways possible only with hydronics. 

 

If your building has an old (20-25+ year) heat plant, it’s likely that, even if the system has been routinely maintained, you’re losing 10 to 20% of the BTUs produced inside it. And if there are performance issues, it’s likely that the old boiler is throwing away a lot more of the heat than that. It’s not at all uncommon for older boilers to cough and sputter through many seasons at less than 50% efficiency.

 

As many boilers reach the end of their useful life, it’s common for flue gas condensate acids to corrode exhaust stacks, for combustion chambers and near-boiler piping to deteriorate. So, it may be time for a systemic overhaul. This article will look at the key parts of what that may entail.

 

Fortunately, there’s no better time to replace an ailing boiler — and other system components — than right now.

Some commercial mod-con systems, for example, have the ability to meet peak demand for space heat and domestic hot water simultaneously. A few years ago, at Fantasyland, Canada’s largest luxury hotel, a contracting firm replaced several old heating systems with high efficiency Rheos boiler/volume water heater units from Laars. The “modulating” function gradually increases or decreases firing based on the call for heat — a huge improvement over old and wasteful, full-fire, on-off operation.  

 

“The boilers are perfectly suited for the job because their controls monitor the demand for hot water and automatically adjusts each boiler’s capacity to meet the required heating load from 1.2 million to 2.4 million BTUs with variability of modulation between 100% and 25% of the input rate,” stated the installing contractor.

 

“They’re an ‘environmental’ win too,” he added. “These are among the ‘greenest’ heating systems on the marketplace with NOx levels of less than 10ppm and low CO2 greenhouse gas emissions, and offer up to 96% efficiency – a big plus in Canada.”

 

“Another key need was the units we selected would need to have a much smaller footprint than the old boilers; the new boiler’s compact size allowed us to install three new units in place of the two older ones,” said the building maintenance engineer. “The high efficiency boilers have also reduced the amount of natural gas required to heat the domestic water, lowering energy consumption and operating cost.”

 

Another facet of a hydronic system overhaul may be piping to and from the mechanical room. At Fantasyland Hotel, the new system was designed so that the mechanical room piping also enhanced overall efficiency and operation. Primary/secondary piping system was designed with total serviceability in mind, incorporating bypass piping so that any piece of equipment within the system can be isolated for maintenance without disrupting the supply of hot water on to the hotel. In addition, the installation there was set up with lead-lag redundancy, exercising each of the boilers uniformly and to permit non-disruptive off cycles for preventive maintenance. 

 

Efficiency is key

 

In the commercial market, we see that “green,” (and to some extent, “high performance”) hydronic heating and volume water heating depends on the interrelationship of four key facets of the boiler system:

 

1. System efficiency. How effectively the boiler relates to the total system is determined by its capacity to deliver heat either quickly, or slowly, depending chiefly on the needs of the system and the ability of the boiler to adjust to changes in the system’s demand for heat.

 

According to Joan Mishou, manager of applications engineering, Laars Heating Systems Company, another important factor is more sophisticated controls that sample changes over time and “learn” the responses of the system to changes in conditions such as heating load, outdoor air temperatures, and firing stages of the boiler(s).

 

Modulating and stage-fired boilers reduce fuel consumption by ‘sizing to the load’ so that the amount of heat produced by the system precisely matches the need.”

 

Piping and pumping are also key factors in building an efficient system. The most efficient boiler in the world can’t make an entire system efficient if the system is not piped and pumped correctly.

 

But efficiency is only one of the advantages of installing these systems. Application of the boiler can play a more important role. Their tough resistance to thermal shock and the ability to accept low return water temperatures puts them in a category of their own and opens up many new possibilities for hi-volume, cold-start systems.

 

“One example is a commercial snowmelt system,” added Mishou. “A condensing boiler takes very low inlet temperatures in stride — in fact, the lower temperature of incoming water (or a water/glycol mix as is usually the case), the higher the combustion efficiency of the boiler.”

 

2. Combustion efficiency & thermal efficiency. Just a few years ago, combustion efficiency and thermal efficiency were considered to be the most important factor in determining overall system performance. That’s not the case today.

According to Mishou, transferring heat from a boiler into a total system — and in just the right amount and at just the right time —– is a truer measure of “green” efficiency and high performance.

 

3. Emissions. To consider the boiler system “green,” the reality of emissions must be taken into consideration.

 

4. The boiler, in context. Of course, what exists beyond the boiler jacket and near boiler piping will impact overall system performance. Consider circulation, control solutions and heat distribution. New technology and intelligent system design are the key players here.

 

Pump system retrofits

 

Does the building have circulatory woes? The solution may involve infinite variables, though — if pumps are old, deteriorating, noisy or otherwise showing their age — it may be time to consider a bigger, better resolution.

 

Drop-in pump replacements are one thing, designed chiefly to solve an immediate need. Pump and circulator technology has come a long way in the past several years, so a more attractive solution for a building retrofit, especially one driven by a desire to enhance overall system performance and reduce energy consumption, would be to study the option of a pump system overhaul. Very often, new pumps provide quick ROI, and payback, save space, and simplify and improve operation of the pumped system — whether for hydronic heating or cooling, movement of process fluids, or to enhance operation of a large domestic water system.  

 

One of the first considerations should be to look at the impact that variable speed pumps could make. The smart circulators can be set to meet the specific needs of a pumped system rather than — as is often the case with single-speed pumps — pumping furiously to meet the need, exceeding it, then shutting off . . . and for the process to repeat itself over and over again.

 

Taco, Inc., one of the leading manufacturers of new, state-of-the-art commercial pump systems, offers LoadMatch as one of the best hydronic heat retrofit options available to building owners today. The cost-effective, single-pipe solution mimics the leading hydronic design used worldwide: primary-secondary pumping (like the design used at Fantasyland Hotel).

The single-pipe LoadMatch system, with its single-pipe primary main, uses terminal units configured with decoupled secondary piping circuits. Maintenance-free wet rotor circulators replace control valves to provide temperature control for each zone. And because the circulators also provide the differential pressure to direct water through the secondary system, there’s no need for energy-consuming control valves or Venturi Ts.

 

And because control valves and balancing valves are eliminated, a single-pipe system also has lower head loss than a conventional two-pipe system; this reduces up-front and replacement costs, saves energy, space and simplifies operation and design.

 

The piped ‘vascular’ system

 

If a building has a two-pipe heating system, this may be the time to consider a single-pipe design retrofit. In the process, consider replacing leaky, corroded, occluded piping with new PEX and EPDM synthetic rubber tubing.  

 

Thousands of miles of copper and steel pipe distribution systems have been replaced with PEX and EPDM tubing. Super durable, flexible, continuous tubing can easily be routed between a source and points of delivery in a fraction of the time it takes to get the job done with metal. And, the material is far less costly. 

 

While you’re at it, it may be feasible to extend some of the new “vascular system” heat into floors, walls, ceilings or new, efficient radiant panels. Efficiency of flow, and heat distribution, dramatically improves overall system efficiency + comfort.

 If parts of a building are being renovated — especially those where achieving maximum comfort is needed, or where large spaces with great ceiling heights that challenge the best forced air systems — ultra-efficient, low-temperature, radiant heat may be a superb solution. 

 

And, finally, there’s the great outdoors. Mother Nature invariably has her way with us during the winter months. One of the best ways to fight back in areas where snow and ice threaten easy passage across driveways, walkways, ramps, stairways and helipads is to install snow melt systems. This involves the embedding of radiant tubing under outdoor surfaces, including concrete, paver bricks, stone, tile and blacktop.

 

Snowmelt systems can be far less costly than requiring people and equipment to clear and dispose of snow and ice. Automatic snow-melting also reduces the need for chemical melting agents that can kill plants, contaminate waterways, and be tracked into interior floors.

 

So, with heating, pumping or piping needs inside the building, or outside, or both — there’s a reasonable, realistic solution. Return on investment is assured.