Architecture

Architecture after the feasibility

24 April 2026Updated 4 July 202615 min readBy Raphael Mwito

Editorial illustration / Architecture

Direct answer

The argument in brief.

Architecture after feasibility is the process of translating financial assumptions into spatial, technical, and operational decisions. Design does not decorate a viable model; it tests whether revenue, efficiency, cost, programme, adaptability, and human use can coexist in one buildable proposition.

Design is not decoration added after the model works. It is one of the mechanisms by which the model works.

01 / The false handover

A spreadsheet cannot finish the architectural brief.

Development teams often describe feasibility as if it settles the important questions. The site has a permissible area. The market supports a price. Construction has a rate per square metre. The model returns a margin. Architecture can now begin.

But the model has not described a building. It has described a set of relationships that a building must somehow make real. Saleable area must become rooms people want. Construction cost must become a structure, envelope, services, and finishes that can be procured and maintained. Programme must become a buildable sequence. Revenue must become a reason for somebody to choose this place over another.

The dangerous moment is the apparent handover from feasibility to design. If the model is treated as settled, architecture becomes a packaging exercise. If design ignores the model, it becomes an argument without economic consequence. Both positions waste the intelligence of the other.

Feasibility establishes what must be true. Architecture tests whether those truths can coexist in one place.

02 / Translate the model

Every financial assumption has a spatial consequence.

The useful question is not whether architects should understand finance or developers should design. It is whether the team can translate assumptions across disciplines without losing their meaning.

Model input

Design translation

Question for the team

Revenue

Product

Who will choose this space, and why this one?

Efficiency

Plan

Which area earns value, and which area makes that value possible?

Cost

Assembly

Where should the building be simple, durable, or generous?

Programme

Sequence

Can design reduce dependencies and protect the critical path?

Exit value

Adaptability

Will the asset remain useful when the first brief changes?

03 / A worked translation

A viable apartment schedule is not yet a viable building.

Consider a hypothetical Nairobi apartment scheme. The appraisal assumes 8,000 m² of gross floor area, 78% saleable efficiency, 96 apartments, a fixed construction budget, and a 24-month programme. All five numbers appear precise. None can be accepted independently.

The model says

78% saleable efficiency

The design must reconcile cores, fire escape, structure, refuse, services, parking access, daylight, and circulation without turning the remaining 22% into an unexplained penalty.

The model says

96 apartments

The plan must show whether the resulting unit widths, wet stacks, frontages, lift demand, parking ratio, and shared services still support the intended market position.

The model says

A fixed cost per m²

The team must define which area receives that rate, what specification it buys, which external and infrastructure works sit outside it, and when escalation enters the programme.

The model says

A 24-month build

The design and procurement strategy must test excavation, structure, envelope, services, approvals, long-lead equipment, commissioning, and the dependencies between them.

The decision is made in the reconciliation.

If the compliant plan reaches only 74% efficiency, the correct response is not automatically to force four points back into the drawing. The team should ask what changed: was the original ratio unrealistic, is the core overprovided, is the unit mix creating excessive frontage, or is a small reduction in saleable area purchasing a product that can command a stronger price and remain easier to operate? The model and the plan should then be rerun together.

04 / Efficiency needs a brief

A ratio tells you how much. It does not tell you how well.

Efficiency is among the most common points of contact between a model and a drawing. It is also among the easiest to misuse. A percentage can reveal whether too much area is being consumed without direct revenue. It cannot, by itself, distinguish waste from support.

A corridor may be non-saleable and still create value by improving privacy, daylight, wayfinding, or the number of viable units. A generous lobby may be unnecessary—or it may make the difference between an address that commands trust and one that feels improvised. A service zone may reduce net area while protecting future maintenance and tenant continuity.

The right target is therefore not maximum efficiency. It is productive area: every square metre carrying a clear role in revenue, experience, operation, resilience, or compliance.

Area that earns

Saleable, lettable, chargeable, or directly productive.

Area that enables

Circulation, servicing, access, structure, and shared experience.

Area that leaks

Residual geometry, duplication, unresolved junctions, and space without purpose.

05 / Where design creates value

Architecture works on both sides of the appraisal.

Design can improve revenue by making the proposition clearer, the product more useful, and the asset more distinctive. It can improve cost by rationalising grids, repetition, spans, wet services, façade modules, and construction sequence. The strongest decisions often do both.

This is why value engineering should begin before a design is produced, not arrive later as a list of things to remove. Early design is the moment to choose the system: where complexity creates return, where standardisation protects delivery, and where flexibility is worth purchasing.

Value upward

Better product-market fit
More usable area
Stronger leasing or sales proposition
Longer relevance and adaptability

Risk downward

Simpler structural and service logic
Fewer exceptional details
Clearer procurement packages
Lower operating and replacement burden

06 / Five design tests

Questions before the drawing hardens.

The user test

Can the intended user understand the proposition in the plan, arrival, light, proportion, privacy, and relationship to the street—not only in the sales language?

The efficiency test

Has efficiency been achieved by removing waste, or by transferring cost into poor circulation, unusable rooms, difficult servicing, and a weaker everyday experience?

The repetition test

What repeats often enough to deserve rigorous resolution? A small improvement to a common bay, bathroom, façade module, or service route compounds across the whole project.

The change test

Which assumptions are likely to move before completion? Structure, grids, access, and servicing should preserve options where the market or operating model remains uncertain.

The whole-life test

Does the decision still make sense when cleaning, replacement, weathering, energy, security, leasing, and future alteration become part of the cost?

07 / A better sequence

Feasibility and architecture should converge, not queue.

The alternative to the false handover is not endless design before commercial discipline. It is a short, deliberate loop. The model establishes the current limits. Design turns them into spatial options. Cost and market testing expose the consequences. The model is revised. The brief becomes more precise.

This loop should happen while the project can still change cheaply. A small number of well-chosen options is more useful than a single concept developed too far. Each option should test a real variable: height against footprint, efficiency against experience, unit count against product quality, capital cost against operational simplicity, or immediate yield against future adaptability.

Frame

Define the user, return, constraints, and uncertainty.

Sketch

Create materially different spatial responses.

Test

Measure area, cost, value, programme, and operation.

Choose

Select the coherent trade-off—not the prettiest image.

Repeat

Carry new evidence back into the model and brief.

The purpose of architecture after feasibility is not to make the numbers look attractive. It is to discover whether the project’s economic promise can survive contact with space, material, construction, operation, and human use.

Test the feasibility calculator →Explore the development lifecycle →

Sources and notes

Evidence behind the argument.

RIBA Plan of Work

Royal Institute of British Architects

A recognised framework for briefing, design, coordination, construction, handover, and use across a project lifecycle.

Construction Input Price Indices

Kenya National Bureau of Statistics

Official evidence on how materials, labour, equipment, and transport costs move through construction delivery.

Related tool

Development Feasibility Calculator