Facility engineers who run chilled-water and hydronic systems hear about nanofluids from time to time, usually as a promise of better heat transfer. Graphene is one of the materials most often studied for this. This article is a careful look at what graphene nanofluids are, what the research says about them in HVAC, what could limit them in a real building loop, and how to approach a trial if you want to find out for yourself. We are deliberately not quoting performance numbers for HVAC here, because a building loop is a different system from a lab rig.
What a nanofluid is
A nanofluid is a base fluid, such as water or a water-glycol mix, with very small particles dispersed in it. The particles are chosen for high thermal conductivity. Graphene is a strong candidate because single-layer graphene has a very high measured thermal conductivity (Balandin et al., Nano Letters, 2008). The idea is that well-dispersed particles can help the fluid carry heat to and from heat exchanger surfaces.
What the research says about HVAC
A recent review of nanofluids in heating, ventilation and air-conditioning systems (Sustainability, 2025) summarises lab and modelling studies on chillers, heat exchangers and hydronic circuits. The overall picture from the literature:
- Many lab studies report improved heat transfer with nanofluids, but the size of the effect varies widely with particle type, loading, temperature and flow.
- Viscosity can rise with particle loading, which can increase pumping energy and offset some of the benefit.
- Long-term stability, particle settling and compatibility with system materials are recurring concerns.
- Full-scale, long-duration building trials are far less common than lab experiments.
In short, nanofluids can help in HVAC, but the evidence is mostly from controlled tests, and a real system needs its own measurement.
Where graphene fluids are designed to fit
Our water-loop products, the ThermaGraph coolant for data centers and the Graphene Coolant Additive for other closed loops, are pre-mixed graphene dispersions designed for closed, filtered loops. For HVAC, a chilled-water or hydronic loop serving a specific piece of equipment, such as a process chiller or a single air handler on its own circuit, is the kind of place where a measured trial makes sense.
Open systems such as cooling towers are a different case. They are exposed to air, debris and water treatment chemistry, and we would not suggest a graphene fluid there without a specific engineering review.
Questions to answer before any trial
- Is the loop closed and isolated? A trial is easiest on a loop you can isolate, fill and drain without affecting the rest of the building.
- What is in the loop now? Water, glycol type and concentration, and the inhibitor package. Compatibility with existing treatment chemicals must be checked.
- What are the materials? Copper, steel, aluminium, elastomer seals and plastics in pumps, valves and coils.
- What filtration and strainers are installed? Fine filters must be checked for compatibility with a dispersed fluid.
- Can you measure it? Flow, supply and return temperatures, pump power and chiller power, logged before and after.
- Who owns the system? Your water treatment contractor and the equipment manufacturer should be part of the conversation, especially where warranties apply.
How to measure a fair result
ASHRAE's guidance on thermal environments and building systems, such as its thermal guidelines reference card, is a useful reminder that operating conditions set the baseline. For a trial:
- Log a baseline period with the current fluid, under similar load and weather.
- Measure flow rate and temperature difference to calculate heat transferred, not just temperatures.
- Log pump power, so any viscosity change shows up.
- Take fluid samples at intervals to check appearance, settling and chemistry.
- Compare like-for-like load conditions, because building loads change with weather and occupancy.
What we do not claim
We do not publish efficiency, energy-saving or heat-transfer numbers for HVAC systems, and we have no HVAC case studies to share. Graphene fluids are designed to help heat transfer in closed loops; whether that shows up in a given building, and by how much, is something only a measured trial can show.
"In HVAC I'd rather under-promise. Pick one closed loop, measure it properly, and let the data decide." — Frans Alkemade
Related reading
For the science and the closed-loop basics, read our nanofluid coolant additive guide, and for data centers specifically, graphene coolants for AI data centers.
Read the coolant additive press release, see the graphene coolants page, or request a quote and a trial discussion.
Frequently asked questions
Can graphene nanofluids be used in HVAC?
They are studied for chilled-water and hydronic loops. A closed, isolated loop with good measurement is the best place for a trial; we do not publish HVAC performance numbers.
Is a graphene fluid suitable for a cooling tower?
Open systems such as cooling towers are a different case and would need a specific engineering review.
What should I measure in an HVAC trial?
Flow rate, supply and return temperatures, pump power and chiller power, compared against a baseline period under similar load.
Will it affect my water treatment?
Compatibility with your existing inhibitors and treatment chemicals must be checked with your water treatment contractor first.
Request a quote, samples or a spec sheet
Tell us your material, the property you want to improve, the carrier you use (water, solvent, resin or oil) and your volumes. Pricing and samples are by quote. Call 704-659-3682 or request a quote, samples or a spec sheet / SDS.
