By Alan Jones
From the October 2024 Issue
As cities continue to evolve and the building sector increasingly focuses on decarbonization, adaptive reuse has emerged as a powerful and cost-effective strategy for revitalizing existing structures. With existing structures accounting for roughly 80% of buildings targeted for decarbonization, repurposing these buildings is becoming a more viable and attractive option. Central to this approach is modernizing HVAC systems, which play a crucial role in enhancing energy efficiency and sustainability in renovated buildings. By integrating advanced technologies and innovative systems, building owners can significantly enhance energy efficiency, occupant comfort, and the long-term viability of their properties.
Yet, updating HVAC systems to meet contemporary energy efficiency standards, improve indoor air quality, and support the building’s new purpose also presents key challenges. In situations where the building use has changed dramatically (such as converting a warehouse into apartments), a completely different HVAC design will be required. Often, the number of zones and the variation in load between zones will change significantly with the new building utilization. To fully unlock the potential of these systems, exploring the aspects of modernizing HVAC systems in existing buildings, assessing equipment reuse, and adopting smart technology is essential.
Modernizing HVAC Systems In Existing Buildings
Many existing buildings have outdated HVAC systems that rely on inefficient technologies, which no longer meet today’s rigorous energy codes. These systems may fall short of providing the required comfort and air quality, and their inefficiencies can lead to higher energy consumption and costs. Upgrading HVAC systems in these projects is essential to align older buildings with contemporary standards.
Retrofitting HVAC systems in existing buildings presents unique challenges, such as limited space for new equipment, aging ductwork, and maintaining the building’s historical integrity. However, upgrading these systems is not just about replacing old equipment; it involves a comprehensive redesign that considers the unique characteristics of the building.
With a global warming potential (GWP) of zero, water is the most efficient, sustainable way to move British thermal units (BTUs) through building distribution systems. Although most existing commercial buildings over three floors have hydronic heating and cooling systems, many of these structures, especially those built before the implementation of modern thermal regulations, are inefficient. As the building sector shifts from gas-fired boilers to water-source heat pumps to reduce carbon emissions and improve energy efficiency, hydronic systems are favored for several reasons, including:
- They offer adaptable, efficient heating and cooling delivery, compatible with a wide range of current and future energy sources, including thermal, electric, and refrigerant-based heating and cooling sources.
- Water is non-toxic and readily available.
- Water has a GWP of essentially zero, which means it does not contribute significantly to the enhanced greenhouse effect that is driving climate change. As such, it is one of the most efficient and sustainable mediums for heat transfer.
- Water’s thermal storage capabilities make it versatile for both chilled and hot water systems, offering benefits such as continual reuse of existing BTUs within the system, load balancing when operating outside of intended design conditions, and cost savings where power and fuel availability may be limited or expensive.
These advantages demonstrate how hydronic systems present a viable option when retrofitting existing commercial buildings to reduce a building’s carbon footprint, aligning with broader sustainability goals and achieving certifications such as LEED or WELL. As these advanced systems are integrated, the next step is evaluating the potential for reusing existing equipment to further improve energy efficiency and lower carbon emissions.
Assessing Equipment Reuse
To determine if existing HVAC equipment can be reused, a thorough evaluation of the current building conditions and energy performance needs to be conducted. This provides a better understanding of the original system design and overall equipment selection.
Although the objective is to reuse as much existing equipment and piping as possible to save costs and minimize construction disruptions, designers must consider the condition of existing equipment during their analysis. Outdated or poorly maintained systems may not meet current performance standards, leading to inefficiencies or failures that could negate any initial savings.
Assessments also need to consider established engineering principles of performance applied in hydronic system design and operation. That includes determining the overall building load profile, potential coil reuse, outdoor reset ratios and identifying the critical circuit.
Once the final assessment is complete, existing hydronic components identified for reuse can be configured for the new system design and enhanced with smart technology to further improve performance.
Adopting Smart Technology To Realize System Potential
The integration of smart technology is transforming how HVAC systems are managed and optimized, particularly in adaptive reuse projects. Today’s advanced technologies, combined with product enhancements, enable continuous monitoring of system performance and environmental conditions, enabling real-time adjustments to optimize efficiency and reduce energy consumption.
Upgrading to ECM (electronically commutated motors) with variable speed controls, which often include pre-programmed modules like the motor, impeller, and balancing valves, can enhance energy efficiency and comfort. Smart motors are designed to save energy and improve comfort; however, it’s crucial to assess the existing pump system to ensure compatibility and avoid extensive rework. If challenges like head loss arise, primary-secondary pumping can offer a solution by dividing the system into manageable sub-zones, allowing for more efficient operation.
Today’s smart motor-enabled pumps allow for the potential benefits of higher operating speeds and/or smart parallel pumping that further increase efficiencies, allow for redundant capacity, and reduce footprint and installation complexity versus legacy systems.
By adopting smart technology, building managers gain enhanced control and deeper insights into their HVAC systems, leading to more informed decisions and long-term operational savings.
Modernizing HVAC systems in adaptive reuse projects is not just about upgrading to the latest technology; it’s about contributing to global sustainability efforts while ensuring economic viability for building owners. As the commercial building sector is faced with increasingly aggressive decarbonization targets, upgrading systems to meet contemporary standards, assessing the viability of reusing existing equipment and integrating smart technology, building owners will ensure the most adaptable, efficient delivery of heating and cooling to provide a comfortable, efficient environment for occupants.
References
Jones is a Senior Director of Product Management for Xylem, focusing on green energy solutions and the development of sustainable products for industrial, residential and commercial buildings markets in the Bell and Gossett and Goulds Water Technology brands. He holds a Bachelor of Science in systems engineering from the United States Military Academy at West Point, and a master’s in business administration from Syracuse University.
Do you have a comment? Share your thoughts in the Comments section below, or send an e-mail to the Editor at jen@groupc.com.
