Benefits of Energy Recovery Ventilation Systems for Decarbonization

As the world faces the pressing imperative to decarbonize and confront the challenges posed by climate change, the Architecture, Engineering, and Construction (AEC) industry emerges as a key player in championing sustainable solutions. One proactive approach in achieving decarbonization objectives revolves around the dynamic integration of Energy Recovery Ventilation systems into building HVAC designs. Let’s delve into the extraordinary benefits of Energy Recovery Ventilation systems (ERVs) and explore how they advance the AEC industry to the forefront of decarbonization efforts.

Why Decarbonization Matters

At its core, decarbonization involves the deliberate reduction or elimination of carbon emissions stemming from human activities, with a keen focus on minimizing and ultimately eliminating the reliance on fossil fuels. The combustion of fossil fuels is widely recognized as a primary driver of global warming and climate change, presenting substantial environmental and human health risks.

In the Architecture, Engineering, and Construction (AEC) industry, a substantial responsibility is attributed to carbon emissions, with buildings accounting for approximately 40% of global energy consumption and contributing to 35% of greenhouse gas emissions. Acknowledging this significant impact, it becomes imperative for the AEC sector to actively embrace low-carbon practices and employ technologies capable of effectively curtailing the environmental footprint associated with building activities. This shift toward decarbonization not only aligns with global environmental goals, but it also plays a pivotal role in fostering a sustainable and resilient future for both the industry and the planet.

Understanding HRV and ERV Systems and Their Functionality

There are two similar types of heat recovery equipment used to reduce the energy consumption associated with bringing outside air into a building for ventilation. One is called an HRV (Heat Recovery Ventilator) and the other is called an ERV (Energy Recovery Ventilator). Both systems provide fresh, filtered air to the indoor spaces while exhausting stale, polluted air to the outside.   By doing so, they reduce the need for heating or cooling the incoming air, resulting in significant energy savings.  How they accomplish the energy recovery and the efficiency of that energy recovery are very different, as is the initial cost of the equipment.

The terminology is a bit confusing, so let’s start with a basic understanding of what the term “heat” is as applied to HVAC systems engineering.   Heat is made up of two components. One component is called the “Sensible Heat”, which consists of the energy associated with of the temperature of the two airstreams in the recovery system. 

The other component of heat in an airstream is the “Latent Heat” component. The Latent Heat is the energy associated with the moisture carried in the air, aka the humidity. Simply put, it is the heat associated with an increase or decrease in the amount of humidity (water) in the air.

The Total Heat is the sum of the two:  Total Heat = Sensible Heat + Latent Heat.  The total heat of the airstream is often referred to as its Enthalpy.

HRV systems, or Heat Recovery Ventilator systems, are mechanical devices that transfer only the sensible heat between the incoming and outgoing air streams in a building. They recover only the “sensible heat” because they only transfer the temperature of the outgoing airstream to the temperature of the incoming air stream.  There is no exchange of humidity or moisture between the two airstreams, therefore there is no transfer of latent heat between the airstreams.      

The energy transfer in an HRV occurs through a heat exchanger, typically either a coil filled with a heat-conducting fluid, such as a refrigerant, or a series of thin metal plates separating the airstreams allowing for the direct transfer of temperature between the two airstreams. The heat exchanger facilitates the movement of warmth from the warmer outgoing air to the cooler incoming air during the winter, effectively preheating the air, or the reverse in the summer, precooling it before it enters the building.

ERV systems, or Energy Recovery Ventilator systems, take HRV to the next level by recovering not only sensible heat but also the latent heat by transferring both temperature and humidity between the two airstreams. ERVs are more complex and more expensive than HRVs, however their energy transfer performance is much greater than the sensible only HRV. ERVs outperform HRVs in almost any application, except where total isolation of the two airstreams is a concern.

The energy transfer in an ERV occurs through what is called a “heat wheel” or “enthalpy wheel”.  The wheel is filled with a porous material that is coated with a desiccant such as Silica Gel or other material that is capable of absorbing both temperature and humidity. The incoming airstream passes through one side of the wheel, and the outgoing airstream passes through the other side of the wheel. The wheel turns slowly, thereby transferring both temperature and humidity between the airstreams. In the winter, the cold, dry outdoor air is preconditioned by transferring both the warmth and the humidity of the exhaust air to the incoming air. In the summer, the dryer, cooler air being exhausted preconditions the incoming air by both cooling it and removing some of the humidity in the outdoor airstream.

These systems, crucial for enhancing both indoor air quality and energy efficiency, are widely deployed in diverse settings. Common applications include residential, commercial, and industrial buildings, along with specialized environments like hospitals and laboratories. The versatility of these recovery systems makes them integral to creating healthier and more sustainable indoor environments across various sectors, while saving a significant amount in energy costs of operating the building.

Benefits of Recovery Ventilation Systems for Decarbonization

Heat and Energy Recovery Ventilation systems play a crucial role in contributing to decarbonization efforts through several key benefits:

Energy efficiency

HRV and ERV systems aid in energy conservation by reducing the amount of energy required for heating and cooling ventilation air in buildings. This results in carbon reduction and cost savings on energy bills, as well as decreased reliance on fossil fuels.

Improved indoor air quality

In the realm of indoor air quality enhancement, ERV and HRV systems excel by delivering fresh, filtered air to building occupants. This proactive approach diminishes exposure to indoor pollutants such as carbon dioxide, volatile organic compounds (VOCs), radon, mold, and bacteria. The consequential improvement in indoor air quality enhances the health, well-being, and overall productivity of building occupants.  Ventilation is required by all building codes for all occupied spaces, so by reducing the energy burden of providing fresh air, ERV and HRV systems reduce the overall operating carbon of the building.

Net-zero carbon emissions

The contribution of these systems to carbon emission reduction is very significant, stemming from their capacity to curtail the overall energy requirements for heating and cooling buildings. This alignment, with efforts to achieve net-zero carbon goals and adherence to green building standards, underscores the positive impact of ERV and HRV systems on environmental sustainability.

Enhanced comfort

ERV and HRV systems go beyond energy efficiency and emissions reduction, actively enhancing comfort levels by ensuring a consistent indoor temperature and humidity level. Introducing pre-conditioned air into the building mitigates issues such as cold drafts, condensation, and dampness, thereby elevating occupant satisfaction and fostering higher retention rates.

Conclusion

Energy recovery systems are a powerful tool for decarbonization, as they offer multiple benefits for energy efficiency, indoor air quality, carbon emissions reduction, and comfort. The AEC industry has a great opportunity to embrace both ERV and HRV systems as a part of their sustainable design and construction practices. If you’re eager to explore the potential of an ERV or HRV system for your project and contribute to a greener and more sustainable future, seize the opportunity today. Contact us, and let’s embark on a collaborative journey to discover the optimal energy recovery solution tailored to meet the unique needs of your project. Together, we can build spaces that prioritize both environmental responsibility and occupant well-being, while substantially lowering operating costs over the life of the facility.