Improvement retrofit: optimising your existing space without disrupting your operations
Three trade-offs that determine your retrofit's ROI
A poorly scoped commercial retrofit means 40% of budget change orders landing six months after signing, most often because of a botched destructive diagnostic carried out upstream. Across 58 Kytom operations with overruns above 5% between 2020 and 2024, the root cause is almost always there: not the worksite, but the audit. Since 2006, we have orchestrated retrofit operations in occupied sites for Asset Managers and real estate departments, over 16 to 28 weeks, with phasing designed to preserve operational continuity throughout the worksite. Our team handles the entire audit, design and delivery chain, and guarantees referenced energy measurement as well as strict compliance with NF S 31-080 on acoustic nuisances in occupied sites. With 11 branches in France and Spain and more than 1200 projects supported since 2006, we arbitrate three structuring tensions: operational continuity versus scope of works, energy performance versus existing building constraints, immediate budget versus 10-year ROI. Here is how we turn these trade-offs into quantified decisions, defensible before an investment committee and sustainable throughout the worksite.
The framework
Three trade-offs that determine your retrofit’s ROI
Every commercial retrofit resolves three quantifiable tensions. We put them on the table from the very first scoping meeting, to prevent them from resurfacing as a change order six months later.
Operational continuity versus scope of works. A simultaneous full-site worksite cuts the total duration by 30%, but requires a complete relocation of your teams. Functional zone-by-zone phasing maintains a large share of activity, at the cost of a few additional weeks.
Energy performance versus building constraints. Commercial buildings from the 1980s-90s frequently cap at 2.50 m under a false ceiling, which limits the integration of a dual-flow HVAC system. The tertiary decree imposes precise energy monitoring and steers towards prioritising envelope renovation.
Immediate budget versus 10-year ROI. The gap between a cosmetic renovation and a heavy restructuring is not read through works logic, but through cash-flow logic.
| Level | Cost €/m² excl. tax | Estimated energy gain | Duration |
|---|---|---|---|
| Cosmetic | 300-450 | low | 8-12 wks |
| Intermediate | 500-750 | moderate | 14-20 wks |
| Heavy | 800-1200 | significant | 22-28 wks |
These orders of magnitude are indicative and vary depending on the initial state of the building, its location and the equipment in place.
The intermediate scenario generally comes out ahead in NPV over 10 years as soon as the residual lease exceeds 6 years and green value is factored in at resale. The heavy scenario is only justified for ownership exceeding 12 years or a rental repositioning, with a shift from category D-E to B-C on the commercial energy rating.
Risks you avoid
Four pitfalls that cause 40% of retrofit budgets to overrun
A retrospective analysis of our 58 operations with overruns above 5% between 2020 and 2024, over an average area of 850 m², highlights four causes, ranked by frequency of occurrence.
- Diagnostic limited to the visible. Inspecting ceilings and partitions without destructive surveys on embedded networks alone generates 40% of the change orders observed. Our countermeasure: 8 to 12 destructive surveys per 1,000 m² section, following an internal protocol refined since 2021.
- Underestimated new/existing interfaces. Fluid connections, localised load reinforcement and air-tightness at envelope junctions systematically cost more than in new construction.
- Optimistic scheduling on administrative approvals. Technical inspection, ERP safety commission and network concessionaires significantly extend timelines in retrofit compared with new build.
- Insufficient operator coordination. HVAC shutdowns, acoustic nuisances requiring the provision of individual protectors from 80 dB(A) of exposure and mandatory use from 85 dB(A), as well as poorly scoped worksite access, weigh heavily on occupant productivity in the affected zones.
Our contrarian position: the audit is not a cost to be squeezed. Industry orthodoxy caps the audit budget at 2-3% of works cost. In practice at Kytom, on assets above 1,500 m² with embedded networks and 1980s-90s false ceilings, investing 4 to 6% of works cost in destructive diagnostics and thermography significantly reduces the change-order rate, a budgetary insurance that our operational experience confirms project after project. A reinforced audit is budgetary insurance for the Asset Manager, not a comfort expense to be traded off against the technical packages.
Our honesty
When retrofit is not the right answer
Improvement retrofit is not universally relevant. We tell you so in the steering committee at the end of the audit phase, rather than during the worksite when it is too late to turn back.
Proven structural disorders. If the asset shows evolving cracks, floor subsidence or generalised corrosion of reinforcement, a cosmetic or intermediate retrofit conceals the problem without treating it. We then steer towards a heavy restructuring with full stripping, or even towards demolition-reconstruction depending on the asset’s cost/value ratio.
Area below 400 m² with a short residual lease. Below 400 m² and with less than 5 years of residual lease, the ROI exceeds the effective occupancy duration. A move to an already-renovated asset is more economically rational, even factoring in transfer costs and the restoration of the outgoing lease.
Clear height under slab below 2.80 m. This constraint prevents the integration of an efficient dual-flow HVAC system without touching the structural work. Either you accept a cosmetic retrofit with no strong energy ambition, or you switch to a swing operation with a substitute asset.
Edge effects at both extremes of size. Beyond 5,000 m² with embedded delegated project management, the interfaces item becomes secondary and multi-package coordination accounts for 50 to 60% of change orders. On micro-operations below 250 m², the pitfall is the reverse: over-instrumentation of the diagnostic absorbs more budget than it secures.
This honesty in scoping is an integral part of our method. Better an audit that concludes « do not undertake this retrofit » than a poorly calibrated worksite that overruns the initial budget by 40%.
Method
- Technical audit (weeks 1 to 3)
Complete structural diagnostic, exhaustive survey of existing networks, referenced energy performance measurement, targeted destructive surveys on 8 to 12 points per 1000 m² section. The deliverable is a quantified audit report accompanied by a matrix of technical and budgetary risks, directly usable in an investment committee. - Cost/impact matrix (week 4)
Each improvement identified in the audit is scored on three weighted criteria: impact on operations, 10-year ROI, technical complexity. The scoring objectifies the trade-offs and allows the Asset Manager to defend the works trajectory before their investment committee, without subjective debate on priorities. - Phase scenario planning (weeks 5-6)
We define the sequences that minimise business impact, working directly with your operator to set the intervention windows. The deliverable is a contractually validated functional zone-by-zone schedule, which secures 70 to 80% of activity throughout the worksite. - Integrated design (weeks 7 to 12)
Production of 3 to 5 technical variants per critical package (HVAC, electricity, partitioning, envelope), with joint validation of interfaces by Kytom’s design and works teams. This integration eliminates the classic breaks in responsibility. Deliverable: complete tender documents and firm committed costing. - Coordinated management (weeks 13 to 28)
Weekly review with your operator, schedule adjustment as worksite discoveries arise, continuous measurement of acoustic nuisances with a 55 dB(A) threshold in occupied sites. Final deliverables: zone-by-zone handover, end-of-works file and post-delivery energy assessment to feed into.
Frequently asked questions
How long does a commercial retrofit in an occupied site take?
Across our recent retrofit operations in occupied sites, the duration generally ranges between 16 and 28 weeks depending on the scope of works. A cosmetic renovation fits within 8 to 12 weeks. An intermediate level, at400-750 €/m² excl. tax with 20 to 30% energy gain, requires 14 to 20 weeks. A heavy retrofit, at 800-1200 €/m² excl. tax with 35 to 45% gain, runs over 22 to 28 weeks. Zone-by-zone phasing adds a few weeks to the raw duration, but preserves the bulk of activity and avoids the cost of a complete relocation.
What budget should be planned for the preliminary diagnostic?
Industry orthodoxy caps the audit at 2-3% of works cost. In practice at Kytom, on assets above 1,500 m² with embedded networks and 1980s-90s false ceilings, we recommend 4 to 6% of works cost to incorporate destructive diagnostics, thermography and targeted surveys. This reinforced investment significantly reduces change orders during the worksite, by limiting unforeseen discoveries on networks and structures. On an operation of 850 m² at 600 €/m² excl. tax, i.e. around 510,000 € of works, the audit gap represents 15,000 to 20,000 € that secure up to 130,000 € of potential change orders.
Can activity really be maintained during a heavy retrofit?
Yes, provided you accept functional zone-by-zone phasing and a 22 to 28-week schedule instead of a shorter simultaneous worksite. Our feedback covers 34 operations in occupied sites between 2022 and 2024: 70 to 80% of workstations remain productive throughout the worksite phase. The strict condition is coordination with your operator: HVAC shutdowns scheduled outside peak hours, acoustic nuisances kept below 55 dB(A) in occupied zones, segregated worksite access. With poor coordination, occupant productivity drops by 15 to 25% in the affected zones.
