How We Test Design Before You Build

3D, Energy and Cost Modelling Explained

Designing or renovating a home is one of the largest investments most people make.

Many of the most important decisions are made before construction begins. Decisions about space, comfort, performance and cost shape the outcome long before a contractor arrives on site.

When those decisions rely on guesswork, problems tend to appear later. Rooms feel darker than expected. Budgets stretch. Extensions overheat. Details clash during construction.

At Studio CMA, we test design before it is built.

We use three complementary models:

• A 3D spatial model
• An energy performance model
• A cost forecast model

Together, they form a structured part of our architectural approach. They sit within our wider framework for architect-led renovations in London, guiding projects from early appraisal through to construction.

These models allow you to see, measure and evaluate your home before committing to build.

The 3D Model — Experience Your Home Before It’s Built

Traditional drawings are useful for architects, but abstract for most homeowners.

A 3D architectural design model turns flat plans into an experience you can see and understand.

We build these models early in the concept design stage, testing the overall massing and volume of the house in context.

It helps us explore how new space interacts with the existing structure, garden, and daylight.

We can experiment with roof forms, extensions, and interior layouts before a single line is finalised.

During Stage 3, the model becomes more detailed — adding openings, materials, and finishes.

We test proportions, shadows, and relationships between inside and out.

Sometimes we develop the model from the inside out, creating a 3D interior design model that studies how natural light moves through rooms and how spaces connect.

By Stage 4, the same model helps refine architectural interiors — built-in joinery, kitchens, and bathrooms — ensuring everything works as part of a cohesive whole.

For clients, the moment they first explore the virtual walkthrough is transformative.

It provides confidence and clarity:

• They can picture the flow of the home.

• They understand how each decision affects light and proportion.

• Couples can evaluate ideas together instead of relying on guesswork.

Many realise they’re not bound by what the neighbours have done — the 3D architectural model shows what’s possible beyond the ordinary.

Why Design Decisions Need Testing

Cost overruns, uncomfortable rooms and awkward layouts rarely begin on site.

They usually begin earlier, when design choices are made without being examined from multiple angles.

A planning approval does not guarantee buildability.
A well-composed drawing does not guarantee comfort.
An early estimate does not guarantee financial alignment.

The design phase replaces assumption with measured analysis. Testing decisions at this stage improves clarity and limits avoidable change later.

Model One: 3D Spatial Modelling

The first model focuses on how your home will feel and function in space.

A 3D model is not simply a visual tool. It is a working model that allows us to examine proportion, volume and coordination in detail.

Seeing Space Clearly

Traditional plans are abstract and require experience to interpret.

A 3D model makes ceiling heights, room relationships and circulation patterns immediately understandable. You can see how an extension connects to the garden, how roof forms sit within the street and how internal spaces relate to one another.

This supports clearer decision-making and reduces late-stage revisions driven by misunderstanding.

Testing Daylight and Proportion

We analyse how natural light enters the home throughout the day and across seasons. Window positions, rooflights and internal openings can be adjusted before they are fixed.

This helps prevent dark interiors, glare and poorly balanced façades.

Coordinating Structure and Joinery

As the design progresses through RIBA Stage 2 and Stage 3, the model becomes more detailed. RIBA Stage 2 defines overall form and layout. Stage 3 refines the design for planning and technical coordination.

At this stage we review:

• Structural zones
• Stair geometry
• Built-in storage
• Kitchen and bathroom layouts

Resolving these elements digitally reduces clashes during construction and supports smoother delivery on site.

The 3D model ensures the spatial experience is carefully examined before work begins.

Model Two: Energy Modelling for Home Design

If the 3D model addresses experience, the energy model addresses performance.

This is particularly important in London’s Victorian and Edwardian housing stock, where extensions and retrofits must improve comfort without compromising the existing building fabric.

We use tools such as PHPP, the Passivhaus Planning Package. PHPP is a detailed calculation method that predicts how much heat a building will lose, how much it will gain from the sun and whether it is likely to overheat.

This modelling approach is closely aligned with the principles outlined in our guide to the Passivhaus standard explained, which explores how fabric performance is measured and verified.

Testing Performance in Plain Terms

Energy modelling allows us to simulate your home over a full year of UK weather conditions.

We can adjust one parameter at a time and measure the impact:

• Insulation levels
• Glazing specification
• Airtightness targets
• Shading strategies

This makes trade-offs visible. Clients can see the performance benefit of additional insulation or the overheating implications of increased glazing.

Moisture and Overheating Risk

For solid-wall period homes, moisture behaviour is critical. Poorly considered insulation can trap moisture and undermine long-term performance.

Energy modelling allows us to evaluate wall build-ups before they are constructed.

We also test overheating risk. Large areas of glazing may increase daylight but reduce comfort if not carefully balanced.

This model supports a fabric-first strategy, improving the building envelope before relying on mechanical systems or renewable technology.

The result is a home that is more comfortable, efficient and durable.

Model Three: Cost Forecasting in Renovation

Design quality and performance must remain aligned with budget.

Our cost forecasting model begins early and develops alongside the design. It is not a contractor’s quote. It is a structured financial forecast informed by current market data.

This work connects closely with our approach to early cost planning, which protects renovation budgets by aligning scope and financial parameters from the outset.

Establishing Financial Parameters

Before the design progresses too far, we establish a realistic cost range aligned with your scope and likely contractor profile.

This prevents a situation where a design is approved but financially unviable.

Testing Financial Impact

As the design develops, we examine how specific decisions affect overall cost:

• Extending further into the garden
• Changing façade materials
• Increasing glazing ratios
• Upgrading performance standards

This allows ambition and affordability to remain aligned.

Maintaining Control

Small additions accumulate quickly. Without structured oversight, projects can drift beyond intended budgets.

The cost model supports prioritisation. It also provides clarity when tenders are received, ensuring comparisons are made on a consistent basis.

Clear cost forecasting contributes directly to transparent discussions about architects’ fees in London, as clients can see how time invested in design coordination protects construction expenditure.

Bringing the Models Together

Each model addresses a different dimension of the project:

• Spatial quality
• Building performance
• Financial alignment

Used together, they create a disciplined and integrated preparation phase.

By the time construction begins, the project has been examined from multiple perspectives. Spatial relationships have been tested. Fabric performance has been evaluated. Budget implications have been reviewed.

Construction remains complex, but disciplined preparation improves clarity and limits avoidable change.

For period homes in East and North London, where extensions and retrofits must balance heritage, performance and cost, this structured approach is essential.

Design is not simply about producing drawings. It is about examining decisions before they become expensive.

Next Step

If you are planning a significant renovation, extension or retrofit, the most effective place to begin is a structured home visit and appraisal, where we assess your property, understand your ambitions and outline how spatial modelling, energy testing and cost forecasting would apply to your project.

Disciplined preparation at the outset supports steadier progress through construction.