11.02.2026

Blog

Installing a heat pump without disrupting your tenants

In practice – Insights from Julien Thirifays, Energy Expert at Pulse

Behind every successful revalorisation lies a series of smart technical decisions. Among them, the switch to heat pumps has become one of the most strategic — and sometimes misunderstood — steps toward decarbonising existing office buildings.

For many investors and asset managers, the question is no longer whether to move away from fossil fuels, but how to do it without jeopardising tenant comfort, operational continuity, or asset value. Especially on occupied sites, this transition raises legitimate concerns.

A clear regulatory signal: the end of fossil fuels

In dense urban environments such as Brussels, the regulatory and market context is clear: fossil fuels are being phased out. New buildings are already subject to these rules: since 1 January 2025, the installation of new gas or oil boilers has been prohibited in new buildings or those treated as new. This ban will be extended to major renovations from 1 January 2030.

In this context, heat pumps are no longer a marginal option but are becoming the technical backbone of future-proof buildings.

Why heat pumps matter today

While geothermal systems offer excellent performance, their implementation in renovation projects is often constrained by access, permitting procedures and ground conditions. In practice, air-to-water heat pumps have therefore emerged as the most realistic and scalable solution for urban office buildings. They can be installed on rooftops or limited ground surfaces and integrated into existing hydraulic networks.

Depending on the scope of works, these systems can either enable a fully fossil-free building, or be deployed as part of a hybrid configuration, where a gas boiler remains as backup during extreme cold spells. In such hybrid scenarios, heat pumps typically cover more than 75% of annual heating demand — already a major step toward decarbonisation.

The real challenge: installing heat pumps on an occupied site

Installing an air-to-water heat pump in an existing building is never a plug-and-play exercise. On an occupied site, several constraints must be carefully anticipated.

Space and structural capacity come first. Heat pumps designed to serve large office buildings are substantial pieces of equipment. Rooftop installation is often the preferred option, but roof load capacity must be assessed in detail, and reinforcements may be required.
Acoustic performance is another critical factor. Producing heat from ambient air requires moving large air volumes — and that can generate noise. In dense urban contexts, acoustic regulations have become increasingly strict. Machine selection, anti-vibration mounts, silencers and acoustic screens are therefore not optional add-ons, but integral parts of the design.
Hydraulic integration is often the most decisive technical constraint. Heat pumps deliver their best performance at relatively low temperature levels (around 35°C for surface heating systems, and up to 55°C for fan-coil–type applications). However, many existing buildings were designed to operate at much higher temperatures (60 to 90°C). If heat emitters are replaced — for example with climate ceilings or modern fan-coil units — performance can be optimised, but this implies intrusive works and temporary impacts for occupants.

What does this mean for tenants?

During works, temporary disturbances are sometimes unavoidable: noise, logistical constraints or partial relocation during technical interventions. However, with proper phasing, clear communication and smart scheduling, these impacts can be significantly reduced. In some cases, flexible work arrangements (remote work or flexible working hours) or phased floor-by-floor interventions allow buildings to remain largely operational.

Once in operation, the benefits for occupants are tangible. Modern heat pump systems, often combined with climate ceilings, deliver a more stable and comfortable indoor climate, with reduced air movement, improved thermal comfort and ultimately more usable space. Beyond comfort, tenants increasingly value the carbon performance of the buildings they occupy — a factor that now plays a role in employer branding and ESG commitments.

Financial logic beyond short-term ROI

From a purely operational cost perspective, heat pumps remain sensitive to the electricity-to-gas price ratio. Studies by the CREG (May 2025) suggest that for residential users, heat pumps are currently not cost-competitive compared to natural gas condensing boilers. In the tertiary sector, the situation is generally more favorable, as electricity prices are often lower, although payback periods still tend to be around 15 years— but focusing solely on short-term ROI misses the bigger picture.

EPB & CO2 impact

Based on the analysis of our recent audits, when correctly sized, heat pumps alone can improve a building’s EPB score by 19 to 25%, directly enhancing asset value. When combined with the full set of optimisation measures identified in our studies, the overall EPB performance improves even further. This strengthened performance supports alignment with EU Taxonomy requirements, facilitates access to green financing, and improves eligibility for certifications such as BREEAM In-Use.

On average, the reduction in CO₂ emissions linked to converting a building to fossil-free energy is 42%.

Improvment of EPB-label with air to-water heat pump

Investment ranges

Typical investment ranges observed today are:

Fossil-free scenarios: ± €50 to €140/m²
Hybrid scenarios: ± €35 to €65/m²

CAPEX air-to-water heat pumps

Pulse’s role: from complexity to clarity

At Pulse, our role is to reframe energy decisions within their true horizon: the complete decarbonisation of the real estate portfolio. Through our audits and strategic analyses, we help investors move beyond a short-term return-on-investment logic and assess energy choices in light of their regulatory compliance, Taxonomy alignment, and the long-term resilience of their assets.

Installing a heat pump on an occupied site is complex — but entirely manageable with the right expertise and preparation. More importantly, it is a powerful lever to transform regulatory pressure into long-term value creation

Julien ThirifaysEnergy Expert

Thinking about decarbonising your asset without disrupting your tenants?

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Installing a heat pump without disrupting your tenants