Project Intelligence report: Renovation of a 1960s apartment building, Cesta talcev 12 (fictional demo project)

Summary

At concept stage, the project's key decision is sound. It keeps the 1964 brick walls, the RC slabs and the timber roof (described as "in good condition"), so most of the building's embodied carbon stays in place. Both evaluated dimensions (D1 Bio-based and circular materials, D2 Renovation and reuse) are rated "partly addressed". Most new and replacement elements take a linear, fossil-based route. The reusable clay tiles and wooden windows are to be disposed of, with no pre-renovation audit, and the new work uses EPS ETICS, PVC windows, concrete tiles and a steel beam. The biggest single issue is the 4.8 m cut in the load-bearing spine wall and the loss of two flats. The material does not weigh this against a lighter, reversible option, back it with a structural survey, or check it against the co-financing programme's rules. Several questions also need answers before the spring 2027 permit: who owns flats 1 and 2 and how owners will consent; how heat from the central heat pump reaches each flat; how flats will be ventilated after airtightening; whether the shared rooms have step-free access; and what energy target the programme requires.

Strengths

Whole-building reuse: the 1964 load-bearing brick walls, cast-in-situ RC slabs and timber roof structure ("in good condition") are all kept, so most embodied carbon stays in place.
A shared community room (~45 m²) and bicycle/pram storage are added for residents within the existing footprint.
Envelope upgrade and fuel switch are combined: ETICS, 24 cm attic-floor insulation (the attic stays cold), triple glazing, and a central air-to-water heat pump replacing per-flat gas boilers.

New European Bauhaus lens

Sustainable. Keeping the structure, slabs and timber roof and switching from gas to a heat pump is a strong base. The circular case would improve if the clay tiles and window materials were kept or reused and bio-based or separable insulation were tested. The material gives no energy target, calculation, ventilation strategy or embodied-carbon check.

Inclusive. A shared community room and pram/bike storage give residents real shared space. However, step-free access, the route from the entry core, a WC, the ownership and consent route for flats 1 and 2, and noise and fire separation from the flats above are not described. The courtyard stays asphalt parking with no shared outdoor space.

Beautiful. The material includes no elevations, so aesthetic quality can't be judged. Re-laying the original clay tiles and reusing old window sashes as internal glazed screens are low-cost ways to keep visible traces of the 1964 building through the retrofit.

Ranked moves

#	Move	Lens	Impact	Effort	Confidence
1	Before fixing the HEB 240 scheme, commission a structural survey and test a smaller opening or the reuse of existing door openings in the spine wall, so the community room and storage work as two linked rooms. Design the conversion to be reversible: keep risers and wet-room positions and use dry partitions. Check the programme's eligibility rules (unit count, residential share) before the permit application.	D2	high	low	high
2	Keep the original clay tiles. Have a roofer survey them (share of cracked or spalled tiles, frost test on a sample), then strip the roof, fit a new vapour-open underlay and counter-battens, re-lay the sound tiles and top up with reclaimed tiles of the same profile. If replacement is still needed, record why, and sell or salvage the sound tiles rather than landfilling them.	D1	medium	low	high
3	Commission a short pre-renovation audit (reusable items, hazardous materials, waste streams) following the EU C&D waste protocol guidelines, and base the tender on it. Write separate collection or take-back for old windows (timber, glass, metal) and boiler/flue components into the contract. Offer sound window sashes to reuse networks, for example as glazed screens for the community room or bike store.	D2	medium	low	high
4	Draft a simple renovation-roadmap step plan for the occupied building. Do the works that need scaffolding (ETICS, windows, roof) in one go so junctions are detailed once, then the heat-pump changeover riser by riser. Agree a short disruption schedule per flat with the owners to support consent and the funding timeline.	D2	medium	low	medium
5	Ask the structural engineer to size a glulam (GL24/GL28) or LVL beam alongside the HEB 240. The check should cover fire resistance, deflection under the brick wall above, and whether the beam could bear straight onto the existing wall returns without new columns. If steel stays, look for a reclaimed section. Run a light Level(s) indicator 1.2 comparison (A1–A3 plus replacement) of the 4–5 new element choices to set priorities for the permit design.	D1	low	low	medium
6	Price the envelope options side by side. For the walls: EPS (baseline), mechanically fixed mineral wool and wood-fibre ETICS, checking programme acceptance and façade fire-barrier needs. For the attic floor, consider blown cellulose or wood fibre. Ask for timber or timber-aluminium triple-glazed window quotes alongside PVC, with mechanically fixed frames in every case.	D1	medium	medium	medium

Blind spots: questions the material does not answer

Who owns former flats 1 and 2 today, and how will they become shared space? Will the owners' community buy them out? How will ownership shares, voting weights and future cost-sharing keys for the 7 remaining flats be recalculated, and what level of owner consent is planned for the change of use and the spine-wall cut?Who would ask: Property manager, the two affected owners, the other owners, and the municipality checking who has the right to apply for the permit · The material says flats 1 and 2 become a community room and storage, but it never says who owns them or how the owners will agree to it. Without a clear ownership and consent route, the permit application planned for spring 2027 and the co-financing application could stall. The change also shifts how the cost of the energy renovation is split among fewer flats.

How does heat get from the central heat pump in the former boiler room into each occupied flat? Which risers and distribution route, which emitters (are the existing radiators kept, and are they sized for lower flow temperatures?), how is hot water made, and how will heat be metered and billed per flat? Where does the outdoor unit go, and how loud is it at the nearest windows and neighbours?Who would ask: Renovation and energy auditor, the co-financing programme assessor, and residents of the upper flats · Going from 9 separate gas boilers to one central system is the biggest technical and social change in the brief, but the material only says 'central air-to-water heat pump in the former boiler room'. That room is not shown on the plan. New risers through occupied flats, heat-cost allocation and outdoor-unit noise near the courtyard are often the questions that decide whether owners accept the change and whether it gets funded.

Once the building is sealed with triple glazing, ETICS and no more gas-boiler flues, how will the flats get fresh air and avoid condensation and mould? Is this extra relevant for the north-facing ground-floor community room and bike/pram storage, where wet bikes and prams will be kept and damp at ground level is unknown?Who would ask: Renovation auditor, future residents, and the users of the community room · The material lists airtight measures but no ventilation strategy, and it says nothing about moisture at ground floor. The north band is where the new shared rooms go. Wet storage and a busy community room next to cold former external corners are a common place for mould after a retrofit, and the problem is cheap to design out at concept stage.

How do residents actually reach the community room and the bike/pram storage? The plan puts the stair and entry in the southern band, but the new rooms are in the northern band, on the other side of the spine wall. Is there a door from the entry core, or a new external door to the courtyard? Is that route step-free, wide enough for a pram, cargo bike or wheelchair, and kept clear of the 8 parking spaces? Is there a WC?Who would ask: Municipality (permit and accessibility review), the competition or funding jury, parents and older residents · The plan shows windows on the north facade but no clear entrance to the new shared rooms. A bike and pram store reached through a parked-car courtyard or through steps loses most of its value. Step-free access is also one of the first things a permit reviewer looks at in a change of use.

What fire and sound separation is planned between the new ground-floor community room and bike storage and the flats directly above? This includes the steel beam and columns, the existing RC slab, and charging of e-bike batteries in the store. Who sets the rules on the room's use and opening hours?Who would ask: Residents of the first-floor flats, the fire-safety reviewer, and the property manager · The material keeps the existing slab and adds a steel beam but says nothing about fire protection or sound. Turning private flats into a shared room and a store full of batteries under bedrooms raises the noise and fire risk for upper-floor owners, who need to agree to the project.

What is the current energy class or heating demand of the building, and what target does the national co-financing programme require? Has anyone checked that 16 cm EPS, 24 cm attic insulation, new windows and the heat pump reach that target, including thermal bridges at the ground-floor slab, window reveals and the eaves junction?Who would ask: Co-financing programme assessor and the energy auditor preparing the energy performance certificate · The owners are asking for co-financing, but the material gives no baseline, no target and no calculation. Insulation thicknesses and the heat-pump size were chosen before any modelling. If the measures fall short of the programme threshold, or the heat pump is sized before the envelope is known, the funding or the investment is at risk.

D1 · Bio-based and circular materials partly addressed

The project's biggest circular decision is a good one: it keeps the 1964 brick walls, the RC slabs and the sound timber roof. Most of the new and replaced elements, though, follow a linear, fossil-based route: the reusable clay tiles and the wooden windows are thrown away, and the new work uses EPS ETICS, PVC windows, concrete tiles and a steel beam. At concept stage there are several cheap moves that could change this: keep or reuse the tiles, look at separable or bio-based insulation, and check whether a timber beam would work. A light Level(s) 1.2 whole-life carbon check could compare these options.

Keep the original clay roof tiles and find a reuse route for the removed windows instead of disposing of themopportunity

What the material says: The brief says the clay tiles are to be "removed and replaced with new concrete tiles" while the "timber structure [is] kept" and is "in good condition". The old wooden windows are to be "disposed of". The material gives no reason why the tiles need replacing.

Why it matters here: Clay tiles that are still sound are one of the easiest components to reuse. They can go back on the same battens after a new underlay goes in, and broken ones can be made up with reclaimed tiles. New concrete tiles add manufacturing carbon and cost. They are also usually heavier per m² than clay tiles, so the engineer would need to check the retained rafters and purlins. Disposing of the windows also skips the waste hierarchy. For a modest-budget owners' community trying to cut cost and disruption, keeping the tiles is likely to save money as well as carbon.

Options

Get a roofer to survey the tiles at concept stage: check the share that are cracked or spalled and test a sample for frost resistance. Then plan to strip the roof, fit a new vapour-open underlay and counter-battens, and re-lay the sound tiles. Make up any shortfall with reclaimed tiles of the same profile, for example on the less visible slope.
If replacement can't be avoided, sell the sound tiles or hand them to a salvage dealer rather than sending them to landfill. Write a selective strip-out and reuse clause into the tender.
Before disposal, offer the 1980s wooden window sashes and frames to salvage or reuse networks (sheds, greenhouses, internal glazed partitions such as the community room or bike store screen). Separate the timber, glass and metal so each can be recycled.

Impact: mediumEffort: lowConfidence: medium

Second life for Stanford's signature tiles · sustainable.stanford.edu · built project ✓ verified
Stanford salvaged 141 tons of clay roof tiles from construction and demolition in 2024 and reused them in new construction and renovation, to cut waste and emissions.
Level(s): EU framework for sustainable buildings · green-forum.ec.europa.eu · official text ✓ verified
Level(s) applies circular-economy principles to buildings and can be used to assess and report on the sustainability performance of renovations, including their materials.

RelevantAlready doneWill adoptNot relevant

EPS ETICS and PVC windows: consider separable or bio-based envelope optionspartly addressed

What the material says: The proposal is "ETICS 16 cm EPS + render" on the 38 cm solid brick walls, "24 cm mineral wool on attic floor" and "new PVC triple-glazed windows". The material doesn't compare insulation types, doesn't mention end-of-life, and doesn't discuss moisture behaviour of the brick wall.

Why it matters here: Bonded EPS ETICS is a composite of adhesive, EPS, glass-fibre mesh and render that is hard to separate. EPS from older systems contains HBCD, and incinerating EPS is limited. This is the opposite of design for disassembly. Solid brick walls also tend to perform better with a vapour-open system. Wood-fibre ETICS boards are made for masonry renovation and are vapour-open. They do have a lower reaction-to-fire class (E), so for a 3-storey residential building you would need to check fire barriers and any national limits. They usually cost noticeably more than EPS. Mineral-wool ETICS fixed with mechanical anchors is a non-combustible, more separable option at a middle price. The attic floor is a cheap place to use bio-based material, for example blown cellulose or wood-fibre batts. For the windows, timber or timber-aluminium frames are alternatives to PVC.

Options

At concept stage, price three wall options side by side: EPS (baseline), mineral wool fixed with mechanical anchors, and wood-fibre ETICS. Ask whether the national co-financing programme accepts each one, and check fire-barrier requirements for a 3-storey residential façade.
Swap the attic-floor mineral wool for blown cellulose or wood-fibre insulation. The cost is usually similar, the attic stays cold and ventilated, and there is no façade fire issue.
Ask window suppliers to quote timber or timber-aluminium triple glazing alongside PVC. Whatever is chosen, ask for frames fixed mechanically (not foamed in only) so they are easier to replace later.

Impact: mediumEffort: mediumConfidence: medium

Disposal of exterior ETICS containing EPS (ReSource / recovery-worldwide) · recovery-worldwide.com · research ✓ verified
EPS ETICS are bonded multi-layer systems that are hard to separate. EPS made before 2015 contains HBCDD, a persistent organic pollutant, and the EPS share in waste-incineration feed should not exceed 2 % by mass.
STEICO ETICS – STEICOprotect dry (manufacturer page) · steico.com · professional guidance ✓ verified
The manufacturer lists wood-fibre insulation systems, including external wall insulation, for new build and retrofit, made from renewable raw materials.

RelevantAlready doneWill adoptNot relevant

New spine-wall beam: check a glulam/LVL option and run a light whole-life carbon comparisonopportunity

What the material says: The plan is a "4.8 m opening in the load-bearing spine wall with a new steel beam HEB 240 on steel columns, existing slab above retained". No structural survey or embodied-carbon considerations are given.

Why it matters here: The steel beam and columns are the main new structural elements, and the column footings will probably add new concrete. Over a 4.8 m span, glulam or LVL may work, depending on the slab and wall loads from above, and would lower the beam's embodied carbon. Fire resistance for a ground-floor community room under flats would come from char-depth sizing or plasterboard encapsulation. The connections and bearings need protecting because metal fixings carry heat into the section. The engineer would also need to check deflection limits (to avoid cracking the brick above) and the bearing on the masonry. A short Level(s) 1.2 style comparison at concept stage would show which choices (beam, insulation, tiles, windows) matter most for carbon.

Options

Ask the structural engineer to size a glulam (GL24/GL28) or LVL beam, possibly as twin members, against the HEB 240. Have them check R-rating by charring or encapsulation, deflection under the brick wall above, and bearing pads or steel shoes onto the masonry. Consider bearing straight onto the existing wall returns to avoid adding columns.
If steel stays, check whether a reclaimed steel section is available, and keep the new column footings as small as possible.
Commission a simple concept-stage LCA (Level(s) indicator 1.2, modules A1–A3 plus replacement) of the 4–5 new element choices to set priorities for the permit design and support the co-financing application.

Impact: lowEffort: lowConfidence: medium

Red Stag TimberLab – Fire Performance of glulam · redstagtimberlab.co.nz · professional guidance ⚑ could not verify
Glulam chars at a predictable rate, so the residual cross-section can be designed for fire, and connections need specific protection because metal fasteners carry heat into the section.
Level(s): EU framework for sustainable buildings · green-forum.ec.europa.eu · official text ✓ verified
Level(s) gives core indicators covering carbon and materials over a building's full life cycle, and can be applied to renovations.

RelevantAlready doneWill adoptNot relevant

D2 · Renovation and reuse partly addressed

The basic decision is sound: the 1964 brick building, RC slabs and timber roof ("in good condition") are kept, so most of the embodied carbon stays in place. There are three gaps. The clay tiles and wooden windows are to be thrown away without a resource or hazardous-materials audit. The 4.8 m cut in the spine wall and the loss of two flats are not weighed against reversible or lighter options, or against the funding rules. There is also no phasing plan, even though the building stays occupied.

No pre-renovation audit; reusable clay tiles and old windows are planned as wasteopportunity

What the material says: The material keeps the structure, slabs and timber roof ('good condition'). But it removes the 'original clay roof tiles' and replaces them with new concrete tiles, and the 1980s wooden double windows are 'disposed of'. No reason is given for replacing the tiles. No audit of reusable or hazardous materials (e.g. asbestos in 1960s pipes, boiler flues, floor finishes) is mentioned.

Why it matters here: Clay tiles on a sound roof are one of the easiest things to reuse: they last a long time and can come off, be sorted and go back on once the roof is insulated or felted. New concrete tiles mean new cement-based material and possibly a different roof load. A 1964 building in which residents stay during the works needs a hazardous-materials check before the boilers, flues and windows come out. The EU protocol recommends waste audits before renovation, not only before demolition.

Options

Commission a short pre-renovation audit at concept stage (reusable items, hazardous materials, waste streams), following the EU C&D waste protocol guidelines. Use it as the basis for the tender.
Default to re-laying the existing clay tiles after a condition sort, topping up with reclaimed tiles of the same profile. If replacement is still needed, record the reason (breakage rate, frost damage, programme rule).
Write separate collection or take-back for old windows (glass, timber) and boiler/flue components into the contract, instead of mixed disposal.

Impact: mediumEffort: lowConfidence: medium

EU Construction and Demolition Waste Protocol and Guidelines (European Commission) · single-market-economy.ec.europa.eu · official text ✓ verified
The protocol includes guidelines for waste audits before demolition and renovation works and relies on better waste identification and source separation.
Energy Performance of Buildings Directive (European Commission) · energy.ec.europa.eu · official text ✓ verified
The recast EPBD introduces life-cycle global warming potential reporting, which points to counting embodied carbon, including what is removed and replaced.

RelevantAlready doneWill adoptNot relevant

Change of use and spine-wall opening: weigh a lighter, reversible option and check the funding thresholdpartly addressed

What the material says: Two ground-floor flats become a ~45 m² community room and bike/pram storage. A 4.8 m opening is cut in the 25 cm load-bearing spine wall with an HEB 240 on steel columns. The flat count probably drops from 9 to 7 ('not explicitly stated'). There is no structural survey and no reasoning about alternatives or future use.

Why it matters here: The conversion is a good adaptive-reuse move. But a large cut in a load-bearing brick wall in an occupied building adds steel, temporary propping, new column foundations and cost. Making the steel beam work together with the old brick wall (composite action) is uncertain without a survey. Fewer units can also affect eligibility: the 2024 Eko sklad call for joint renovation of older multi-apartment buildings requires at least 9 separate residential units and 9 owners. If ground-floor housing demand comes back later, a reversible layout keeps that option open.

Options

Test a smaller opening, or reuse existing door openings in the spine wall (community room and storage can work as two linked rooms). Commission a structural survey before fixing the HEB 240 scheme.
Check the eligibility rules of the targeted programme before the permit (unit count, residential share). Consider timing the change of use so it does not jeopardise co-financing.
Design the conversion to be reversible (keep service risers and wet-room positions, use dry partitions) so the space can return to flats.

Impact: highEffort: lowConfidence: medium

Eko sklad public call: loans and grants for joint comprehensive energy renovation of older multi-apartment buildings (Uradni list RS, 2024) · uradni-list.si · official text ✓ verified
Eligible buildings must have at least 9 separate residential units and 9 different owners, with more than 50% residential floor area, and façade insulation is a mandatory measure.

RelevantAlready doneWill adoptNot relevant

No phasing or renovation roadmap for an occupied buildingopportunity

What the material says: The works are carried out 'while most flats are occupied' and owners want to 'minimise cost and disruption'. No sequence is given for the envelope, roof, windows and the switch from per-flat gas boilers to the central heat pump. No energy targets or decant plan are stated.

Why it matters here: Order matters. Sizing the heat pump after the envelope upgrade avoids oversizing. Fitting airtight windows without a ventilation plan risks condensation. Each flat's gas boiler switch-off has to be coordinated with heat distribution. Funding calls also set completion deadlines; the 2024 Eko sklad call allows 12 months from the contract. The recast EPBD promotes renovation passports for owners who renovate in steps.

Options

Draft a simple step plan (a renovation-passport-style roadmap) at concept stage: envelope and roof first, then windows plus ventilation, then the heat-pump changeover by riser. Note which steps happen in occupied flats.
If the budget forces staging, do the works that need scaffolding together in one go (ETICS, windows, roof), so scaffolding is set up once and junctions such as the window-to-insulation detail are done once.
Agree with owners on a short disruption schedule per flat (window day, boiler changeover day) to support owner consent and the funding timeline.

Impact: mediumEffort: lowConfidence: medium

Energy Performance of Buildings Directive (European Commission) · energy.ec.europa.eu · official text ✓ verified
The recast EPBD introduces building renovation passports to guide owners who carry out energy renovation in several steps.
Eko sklad public call for joint comprehensive renovation of multi-apartment buildings (Uradni list RS, 2024) · uradni-list.si · official text ✓ verified
The call requires at least 3 coordinated measures, including façade insulation, and sets a 12-month completion period from contract signature.

RelevantAlready doneWill adoptNot relevant

Information the evaluation was missing

Exact site/plot location, municipality, plot size, site plan, orientation, neighbours, and surroundings
Planning/heritage status, zoning constraints, and whether the building is protected or in a protected area
Structural survey and calculations for the spine-wall opening (load path above, foundations under new columns, temporary works)
Budget figure, programme eligibility criteria and energy-performance targets (current vs. target energy class/kWh/m²a)
Heat pump capacity, sizing, heat distribution (radiators or underfloor), outdoor unit location and noise, hot-water arrangement, and the transition from gas boilers in flats
Reasoning for removing reusable clay tiles; condition, weight and roof loading of the replacement; alternatives such as reusing tiles
Details of windows (frame material, reuse or recycling of old windows), thermal bridging, and ventilation strategy after airtight windows
Fire safety, acoustic separation of the community room from flats above, moisture/damp at ground floor, and asbestos/hazardous material survey
Accessibility: step-free entrance, lift, WC and accessible access to the community room
Courtyard design: permeability, greenery, stormwater, EV charging, bicycle parking outdoors, shading/overheating
Residents' decant/phasing plan and ownership/management model of the community room
Upper-floor plans, elevations, and typical flat layouts; the position of the existing boiler room is not shown on the plan
Drawing scale/dimensions: plan and section are schematic and unscaled; the section does not show floor-to-floor heights

Questions for the architect

Is a structural engineer's survey available to confirm the spine wall is carrying the slab above and upper walls, and what is the foundation condition under the new steel columns?
Why must the original clay tiles be replaced given the good roof structure: are they damaged, or is reuse/retention of the clay tiles an option under the budget and programme?
What are the programme's energy-performance requirements, and have the 16 cm EPS, 24 cm attic insulation and heat pump been modelled against them (including alternatives to EPS such as mineral wool or wood fibre)?
How will the community room be accessed and used (step-free entry, WC, opening hours, noise), and who will own and manage it?
Is there any appetite to reduce asphalt in the courtyard (e.g. partially unseal for planting, stormwater, shared outdoor space) while keeping the 8 parking spaces?