A Guide To Energy Saving Hydronic Additives
Energy saving additives for hydronic systems are the simplest way to instantly reduce building energy consumption and emissions by up to 15%. Most commercial and multi-unit residential buildings use a system of water pipes to deliver heat within a building (See Lead Image). Heated or cooled water is pumped through a network of pipes to deliver or remove heat energy in the building. After delivering its energy, the water returns to be heated or cooled again and the cycle continues until the temperature settings have been reached. Energy saving hydronic additives improve water’s ability to transfer heat, which lowers energy consumption and emissions with a fast simple payback.
How It Works
Energy saving hydronic additives work by reducing water’s surface tension by 60% which improves water’s ability to receive and deliver heat. Think of the water pipes of a boiler system like a network of roads used to deliver heat. The additive is like adding extra lanes to the heat highway, which allows the water to move more heat with each cycle (Figure 1). The process works the same for both heating and cooling applications. Once installed, the system will hit temperature set points quicker, which reduces equipment run times, lowering energy consumption and associated emissions.
Independent testing by universities, engineering research consultants, and hundreds of private case studies have verified that hydronic additives can reduce HVAC energy consumption by up to 15%. The embedded carbon from producing the additive is typically offset from the energy savings within the first few days after installation. The technology has been commercially available for over ten years with hundreds of thousands of successful installations to date. North American case studies are available through Pace Solutions.
The energy savings from the additive provides a simple payback in less than two years for most buildings. Rebates are available from some utility providers which further shorten the payback period. The cost of treatment depends on the size of the HVAC system and typically ranges from $1,000-$50,000. For example, a twenty-story office building with a 12,000-litre boiler system which spends $175,000 per year in natural gas would require a $25,000 additive treatment. The building would save approximately 2,100 GJ of natural gas, lowering utility bills by $21,000 per year. This would also lower the building’s emissions by approximately 158.08 tonnes of CO2e emissions, equivalent to the annual emissions from 33.6 passenger vehicles. Net savings over the first five years would be approximately $80,000, assuming the cost of energy did not increase.
The thermally stable additives are a one-time treatment, with the longest running studies showing continued energy savings for over twelve years. Boiler and chiller systems typically lose less than 5% of total water annually through regular maintenance and inspections so an additional 5-15% top-up may be required every 3-5 years to maintain peak energy efficiency. Automated systems are available to monitor the system and inject additional additives with any water loss (Figure 2).
Current additives on the market can be used to save energy in nearly any closed-loop HVAC system. They are less corrosive than water and non-hazardous to the environment, making them safe for discharge down sanitary sewers. They are compatible with standard corrosion inhibitors and glycol and do not void equipment warranties. It’s recommended to verify these compatibility details with the additive manufacturer before installation.
Additives can be installed via an in-line pot feeder or through an injection pump, similar to adding glycol, inhibitor or other water treatment products (Figure 3). Installation takes around one hour and requires no downtime or setpoint changes for the building. It is recommended to have the additive manufacturer or qualified water treatment provider complete the installation. Commercial plumbers with experience adding inhibitors and glycol can also complete the installation if required.
Measurement & Verification
Verifying energy savings from hydronic additives is achieved by weather-normalizing the HVAC system’s historical annual energy consumption baseline using heating or cooling degree day (HDD/ CDD) values from a local weather station. Once the historical baseline trend is established, the additive is injected into the HVAC system and post-install energy consumption is then weather-normalized and compared against the trendline of the baseline data. The difference between the projected consumption from the baseline trendline and the new post-install consumption trendline determines the annual reduction in HVAC consumption.
In Figure 5, the gray dots represent monthly boiler natural gas consumption prior to adding the hydronic additive. The orange dots represent monthly gas consumption after the additive has been installed. It is recommended to use buildings that have a good correlation between energy consumption and outside temperature to achieve conclusive M&V. Building operations should also minimize any changes that could impact energy consumption immediately before or during the M&V period.