Very High Efficiency HVAC Systems

You cannot discuss or make significant strides in energy efficiency for buildings without looking at HVAC. While lighting has come a long way, as have control, refrigeration and compressed air systems – all buildings have HVAC requirements and few are as efficient as they can be.  In addition – I find that most sustainability led decisions have another reason for investment, and comfort is a huge driving force of capital improvements.

To make this newsletter very timely, we just started up 3 of 6 systems for our first large heat pump system installation for a school and community building in Oak Park IL. Heat pumps use electricity to transfer heat from outside to inside in the winter, and inside to outside in the summer.  Newer generations of systems work well even down below 0 degrees Fahrenheit, and they work almost effortlessly at cooling in the summertime.

The system we are installing is quiet, sophisticated and enables comfort controls not available to this building for the past 70 years.

Years ago, our earliest buildings were heated with wood, then coal, then natural gas. Today, most commercial and municipal buildings have a packaged rooftop system, meaning that the heating and cooling both take place within one system on the rooftop. If you are not sure what all the buzz is about for heat pumps and building electrification, modern heat pump systems are 50% more efficient than standard rooftop systems.

How do we get better

We must make big changes if we are to make a significant difference in the environmental impact of our built environment, since heating and cooling make up the largest proportion of energy consumption for most building types.
There are two ways we can make improvements on HVAC for our buildings – we can make small improvements through technology advances, like adding smart thermostats or replacing current equipment with advanced rooftop equipment.

Alternatively, and I would argue more meaningfully, we can take big leaps and redesign systems. This includes electrifying buildings, using energy recovery ventilators, and Variable Refrigerant Flow (VRF) heat pump systems for a radical overhaul of existing systems. This is the approach we are taking right now with some of our progressive customers.

Heat Pump and VRF System - What is it?

A heat pump is similar to an air conditioner or refrigerator – it uses electricity to take heat from one space and drive it to another. Even on really cold days, there is heat in the outside air that these systems can pull in to warm a space. Modern systems can efficiently heat a space up to -10 degrees Fahrenheit, and they work even lower temperatures than that but with some loss in efficiency. Thousands of buildings in Chicagoland are heated and cooled by heat pumps, and these modern systems work in our cold climate, despite what people may think.

Heat pumps can be either air sourced, which is what we will be focused on today, or ground sourced – which is geothermal heating and cooling. While geothermal is amazing and worth exploring – air sourced is more practical for most buildings in our region.

A Variable Refrigerant Flow (VRF) system is a heat pump system that can simultaneously heat and cool a building by having multiple indoor units transfer heat from one room into another for advanced energy savings (think of one hot sunny room with a cold room on the other side of the building). A large outdoor unit quietly takes energy from the outside air and brings it inside via copper refrigeration lines.

I often think of these systems as more similar to a commercial refrigeration system than a traditional HVAC system – since there are not huge ducts carrying the warm or cool air to the spaces. Instead, insulated refrigeration lines run between each room and quietly bring temperature control to each space. It involves a different way of thinking about a building, and a commitment to improving the space.
Energy Recovery Ventilators are one of the most cutting edge advancements in HVAC right now. First of all, we all understand the value of outside air to buildings right now in terms of Covid and our health. Fresh air means less chance of germs spreading from one person to another.

However, fresh air on very hot or very cold days also means higher energy bills. Your system worked hard to condition a space, and adding fresh air from the outside makes it work harder to warm or cool that incoming air. Local code requires fresh air be brought into spaces, although not all spaces have this if they are old, and even fewer have their systems working properly.  I have seen many times outside air dampers permanently shut or even having cardboard over them to help a system keep up on very hot or cold days.

Understandably, bringing in outside air and energy efficiency are naturally a bit at odds with each other.

ERVs layer the incoming air over the outgoing air to reclaim the heat. Heat moves across the temperature gradient. In the winter, heat is transferred to incoming outside air. And in the summer, heat from incoming air is transferred to the outside. Most of these systems have been 60-80% efficient, but new cellular technologies are up to 93% efficient in this process and can regulate moisture – keeping it out in summer and in during winter. I would estimate that less than 5% of buildings truly have good outside air flow in Chicagoland. This technology brings indoor air quality to the next level, bringing the presence of enough outside air and sustainability in alignment with each other.

ERV + VRF = Very High Efficiency HVAC

This is not a new technology, so the energy savings have been demonstrated in other buildings and pilot programs. In fact, between 2015 and 2018, a pilot study program in the pacific northwest demonstrated HVAC energy savings between 49 – 89%<. Imagine completely removing the gas bill for your building, while your electric bill stays the same – this is shown to be possible. Imagine those same results in thousands of commercial properties in Chicagoland; this would be a meaningful environmental impact.

Rebates from Utilities

Rebates and incentives are readily accessible for commercial and municipal buildings in Illinois, including LED lighting, smart building controls, and energy efficient HVAC systems. Most of these rebates are prescriptive, meaning there is a set rebate value for each item. However, new technologies do not have as much data to base this on so utility rebate systems must continue to research to better understand the savings. Utility companies need data to help build a foundation for rebates and incentives in the future