Modernising Office Comfort: Replacing Chiller & AHU Systems with VRF/VRV Technology
In today’s office environments, thermal comfort, energy efficiency and sustainability are no longer perks, they’re expectations. For many commercial buildings still relying on an ageing chiller and air handling unit (AHU) combination, upgrading to a Variable Refrigerant Flow (VRF) or Variable Refrigerant Volume (VRV) system can offer a high-performance solution with real estate value and regulatory benefits.
But when fresh air delivery is essential, especially in post-pandemic office design, the right approach often means keeping the AHU and reconfiguring your core cooling and heating setup.
🧊 Why offices benefit from VRF/VRV HVAC systems
VRF/VRV systems deliver precise
comfort control across varied spaces. Unlike traditional chiller-AHU setups, they optimise performance for modern offices:
Zoned climate management for meeting rooms, open-plan areas, and cellular offices.
Inverter-driven compressors to match demand and minimise energy waste.
Compact and quiet operation, suited to high-occupancy environments.
Integrated heating and cooling, with heat recovery options in shared spaces.
Improved EPC ratings, essential for compliance and letting potential.
These advantages make VRF/VRV a compelling choice for landlords, FM teams, and tenants alike.
🛠️ Retrofit pathways for commercial offices
Let’s explore the most effective approaches for retrofitting office HVAC systems:
1. Hybrid approach: Retain AHU for ventilation, retrofit with VRF/VRV cooling
Ideal for: Multi-floor offices requiring compliant fresh air and targeted temperature control.
Rather than removing the AHU, retrofit it with a direct expansion (DX) coil from the VRF system. This keeps ventilation compliant with Workplace (Health, Safety and Welfare) Regulations while reducing reliance on outdated chillers.
Key Elements:
AHU retains its ventilation role with added DX cooling from a ducted VRF unit.
Controls updated for simultaneous operation and scheduling.
Fresh air supply can be demand-controlled using CO₂ or occupancy sensors.
Advantages:
Keeps air quality compliant while upgrading temperature control.
Minimises disruption to building fabric.
Reduces energy bills and improves tenant satisfaction.
2. Full Upgrade: Remove chiller & AHU, install complete VRF/VRV system
Ideal for: Offices with redundant or poorly performing AHUs and limited ventilation demands.
In this scenario, both cooling and heating loads are handled by VRF indoor units; cassette, wall-mounted, or slim ducted. Fresh air may be introduced via standalone mechanical ventilation, if required.
Key Elements:
Outdoor VRF units positioned on roof space or external platforms.
Piping routed through ceiling voids or risers.
Indoor units zoned by layout and occupancy profiles.
Advantages:
Maximum efficiency and thermal zoning.
Simplifies building services.
Ideal for Cat A refurbishments or speculative lettings.
3. Phased retrofit strategy
Ideal for: Occupied offices or cost-sensitive refurbishments.
Tackle the upgrade one zone or floor at a time. Start with high-usage areas like client meeting suites or open-plan workspaces. AHUs can be retained during early phases, then phased out as more zones convert.
Key Elements:
Sequenced commissioning aligned with business continuity.
Temporary hybrid operation with legacy components.
Financial planning aligned with lease cycles or fit-out budgets.
Advantages:
Operational continuity during works.
Spreads capital expenditure.
Allows flexibility based on occupier needs and feedback.
🏢 Key considerations in office projects
Before starting your retrofit, assess these factors:
Structural loads on roof and ceiling areas for outdoor and indoor units.
Pipework routing across floors and risers; be mindful of tenant impacts.
Electrical supply existing panels may require upgrades.
Acoustic performance low-noise VRF units reduce ambient distractions.
Control integration connect systems to BMS for smarter operation and TM44 compliance.
🌿 Sustainability & business value
Modern VRF/VRV systems contribute directly to sustainability targets:
Heat recovery options balance energy across zones.
Efficient zoning reduces wasted cooling or heating.
Smart controls enhance performance and reporting.
Improved EPC scores support leasing, regulatory targets, and CSR goals.
Retaining AHUs for fresh air ventilation, even with upgrades, complements indoor air quality (IAQ) initiatives, adding another layer of wellbeing to your office space.
💼 Why it matters
In the competitive office landscape, HVAC upgrades aren’t just a technical fix, they’re a strategic investment. Whether you’re managing a multi-let building or updating your company HQ, transitioning from a legacy chiller/AHU setup to VRF/VRV systems can drive comfort, compliance, and cost-effectiveness for years to come.
