Heat Exchangers: Clearing the air

Building new barns comes with several major decisions. Not the least of which is heating, cooling and ventilation. 

Government financial support, coupled with cost-offsetting benefits, has proven Pondeuses JL Inc. was right to include heat exchangers for its six barns built in 2021 under the Lebco umbrella of agriculture companies. It was a $12 million investment to build the barns. 

While initial costs for the heat exchangers were higher than conventional HVAC systems and cost recovery had not yet been demonstrated in Canada, the resulting increase in production has made it all but a moot point in this case. The farm is an example of how well birds perform when they live in clean air. 

Jocelyn Leblanc, owner of Lebco in Saint Hyacinthe, Que., says the project is a success. He saw his first heat exchanger in use in a laying barn in Holland. 

“We visited the farm in Holland maybe six years ago,” he says. “We decided to go with this project. We arrived at the conclusion it is better because we save energy. I think it is the best way to design a [laying hen and brooding] farm.”

Leblanc’s recently built farm has four barns for layers and two for brooding pullets. All six measure 42’ by 200’ and are arranged in sets of two, end to end. The laying barns are connected at their inside ends with a management and infrastructure building to form an H shape. The pullet barns are not connected. 

The objective and specifics
The goal at the outset of the project was to improve air quality – primarily the reduction of ammonia and carbon dioxide – with ventilation and to reduce harmful emissions without increasing energy costs. Suzelle Barrington, an engineer with Consumaj Inc.’s environmental division, took on the project. 

“The cost, including installation, was $1.1 million for six exchangers,” Barrington says of the ECO Zero heat exchangers made by Vencomatic. 

The project was financially supported in part by Technoclimat through its 2013-2020 Action Plan aimed at climatic change and by The Fonds Écoleader program, supporting ecoresponsible practices and clean technologies.

Heat exchangers work by transferring the warmth from the barn air being pushed out to the fresh air being pumped in. Using conduction, the heat is passed from one mass of air to the other without the two masses merging. 

In the ECO Zero units, some of the inside air can be recirculated and blended with the incoming outside air. If the outside air isn’t warm enough, heaters automatically kick in to warm it before entering the barn. 

Each of Leblanc’s barns has its own heat exchanger. The laying hen barn units have a capacity of 8.3 cubic meters per second and have a long, flexible plastic tube down the centre of the ceiling. This design ensures fresh, heated air is distributed the full length of the barn and eliminates hot or stagnant spots. There is no space wasted and air pressure keeps the tube inflated. 

The brooding barn units have a capacity of 5.6 cubic meters per second and are a centrally located, curtain-controlled system with two fans blowing the air towards both end walls. 

Clearly, with that kind of capacity, these units are unlike the conventional low-flow heat exchangers and ventilation, which struggle to control ammonia and CO₂ levels. Barrington describes these systems as oversized for the winter to provide enough ventilation for summer. This size also allowed testing for how low ammonia levels could be in the winter. They are incredibly powerful, yet don’t have the cacophony of conventional heating units with numerous fans throughout the building.

“There is only one inlet,” she says. “Whereas with the conventional system you’d have fans. You’d have many fans.”

Additionally, many of those conventional system fans can’t be insulated over their own area. The heat exchanger, however, has no cold spots in the barn, ensuring consistent temperatures throughout and less heat loss. 

“The barn is more efficient and airtight,” Barrington says. “You have one unit and it does it all.”

Heat recovery is at least 80 per cent, compared to smaller, conventional heat exchangers, which would be about 50 per cent. Much of the reason for this is the length of the exchange unit itself, which is about 45 feet long.

“We figure the system pays for itself in about five years,” she says. “Even up to zero degrees Celsius, you have over 80 per cent efficiency. You could use a conventional system with high ventilation rates equal to this system, but the propane bill would be enormous.”

Too much of a good thing
The ECO Zero units can keep the ventilation rate high, even in the winter, when low-flow heat exchangers cannot. In fact, the ventilation rate can be set so high that it dries the barn’s air out too much, especially given the dryness of winter air. 

This was the case when Barrington and Leblanc tried to get the ammonia rate down to 10 ppm. 

“At 10 parts per million, the barn was too dry,” she explains. “The air flow required to reach 10 ppm of ammonia was too high despite the fact that heating costs would not necessarily be higher.”

Instead, they settled on the Canadian preferred standard of 25 ppm as a benchmark, which it handles easily. 

“The higher flow rate with the lower energy costs with this system allows Monsieur Leblanc to keep the ppm rates below 25 ppm,” she says. 

All of this is done through sensors and automation. Leblanc gets alerts and notifications as needed. He says the control of the barns is very easy because there is only one heat exchanger unit per barn. 

“The system’s data can be transferred to a mobile phone or similar device,” says Barrington. “[Information is] based on temperature, relative humidity, CO₂ readings and more. This way, it is one big ventilation system which is the heat exchanger with the heat unit and those controls.”

The Leblanc family had six heat exchangers installed, which they say has helped boost egg production.

Benefit to the birds
Happy birds are productive birds. “The animals, the more you look after them, the better they will do for you,” she says. 

And ultimately, that was the result Leblanc was after. In the new barns, there is no stress from an HVAC system. It’s quiet, with a consistent temperature throughout and no moisture. “There’s absolutely no dust,” says Barrington. “And the laying hens are noisier than the system.”

The end result is more eggs. And as Leblanc notes, the quality of the eggs is very good. “We need to push more feed because we continue to get more eggs,” he says. “The feed rep comes to the farm and says, ‘reduce the feed,’ I say, ‘we can’t, we have good eggs,’ we have more eggs.”

With less ammonia in the air, birds stay healthier. “With conventional ventilation systems, ammonia levels can remain above 40 ppm in the wintertime, which is very high,” says Barrington. “These high levels and even higher close to the floor where the manure lies, tends to burn the eyes of the birds is what I’m told. They can’t find the feed. This has a major impact on the birds.”

It also has a positive impact on employees who are no longer exposed to those high levels of ammonia and CO₂. 

The last word
But putting it all on paper, are the ECO Zero units worth it? Leblanc says so and so do the numbers. Barrington followed the project for two years to ensure results stayed positive. 

The investment for the heat exchange system, broken down by bird, is much higher at $5.80 compared to $0.60 for a conventional system; the electricity cost is also slightly higher at $17.99 per bird compared to $14.01 in a conventional system. 

However, medication costs have dropped to zero and fuel for heating dropped from $0.98 a bird to $0.66 a bird. 

This represents a $24.45 cost per bird as opposed to a $15.83 cost per bird – an increase of $8.62 per bird. If that were the only outcome, it would be a short story. But as previously noted, healthier birds are happier birds and happier birds are more productive.  

Leblanc and Barrington witnessed an increased revenue to $57.20 a bird compared to $37.64 per bird in a conventional system. At an increase in revenue of $19.56 a bird, Leblanc is netting $10.94 more per bird due to the heat exchange system. 

Moving to a heat exchanger like ECO Zero as opposed to conventional HVAC systems or conventional heat exchangers is a large financial outlay at the start, but the benefits are there for the long term.