Part O Overheating Assessments delivers compliant thermal modelling for new residential developments in Eastbourne and across the UK.

As we focus solely on Building Regulations Part O, our assessments are accepted by planning officers, Building Control, and design teams nationwide.

Since we carry out overheating assessments using CIBSE TM59 and dynamic simulation modelling, clients rely on us to identify risk early and avoid delays.

Send your plans to receive a fixed quote and ensure your design meets Part O from day one.

What Is a Part O Overheating Assessment in Eastbourne?

A Part O overheating assessment in Eastbourne is a compliance report that tests whether indoor temperatures remain within acceptable limits during summer.

It uses CIBSE TM59 or dynamic simulation modelling to calculate risk, because Part O requires new dwellings to limit solar gain and provide effective heat removal.

As overheating affects both occupant health and planning approval, the assessment must be completed before construction or sign-off.

When Is a Part O Overheating Assessment in Eastbourne Required?

Overheating assessments in Eastbourne are required for all new residential buildings regulated under Part O.

They are typically submitted during early design or planning, because thermal performance must be demonstrated before approval.

Since overheating mitigation is most effective at concept stage, early modelling avoids expensive redesigns later in the project.

How Much Does a Part O Overheating Assessment in Eastbourne Cost?

The cost of overheating assessment in Eastbourne range from £395 to £1,200 + VAT.

The cost depends on the building type and complexity.

The final price reflects factors such as number of units, floor area, window ratios, and ventilation strategy, because each affects simulation time and modelling detail.

Since compliance issues discovered late can result in delays or failed applications, early instruction offers both cost savings and certainty.

What Are the Benefits of a Part O Overheating Assessment in Eastbourne?

A Part O overheating assessment in Eastbourne improves design quality, supports compliance, and protects occupant comfort.

Key benefits include:

• It demonstrates compliance with Building Regulations Part O – because it proves your design meets indoor temperature limits.
• It supports planning and Building Control approval – because formal overheating evidence is now a standard submission requirement.
• It reduces design risk – because thermal issues can be identified and corrected before building.
• It improves occupant well being – because overheating is linked to discomfort, poor sleep, and heat-related health risks.
• It reduces reliance on mechanical cooling – because the report supports passive design and natural ventilation strategies.
• It supports SAP and energy reporting – because the thermal model integrates with wider compliance packages.
• It adds long-term value – because thermally resilient buildings are more marketable and more comfortable to live in.
• It addresses future climate risk – because assessments use current and projected weather conditions.

Who Needs a Part O Overheating Assessment in Eastbourne?

Part O assessments in Eastbourne are needed for any new residential development introducing habitable rooms.

This includes houses, flats, student accommodation, care homes, and conversions, because all dwellings must meet national overheating limits.

As local authorities enforce both Part O and additional local policies, a compliant report is essential for planning approval.

What Does a Part O Overheating Assessment in Eastbourne Involve?

The assessment in Eastbourne uses software modelling to predict internal temperatures across summer conditions.

It factors in glazing, solar gain, ventilation, occupancy, and building orientation, because each element directly influences internal heat levels.

As the model identifies rooms likely to exceed comfort thresholds, it provides evidence for design compliance or recommendations for improvement.

What Methodology Is Used for Part O Compliance?

Part O assessments follow CIBSE TM59 or dynamic simulation modelling (DSM), depending on the complexity of the scheme.

TM59 uses standardised inputs and thresholds to test temperature exceedance in bedrooms and living rooms.

As some buildings require greater flexibility in ventilation modelling or zoning, DSM may be used where TM59 alone is insufficient.

Since most planning authorities reference these methodologies in their validation criteria, reports must follow accepted formats.

Can We Provide Advice if the Design Fails?

We offer practical feedback when an initial design does not meet Part O performance targets.

Suggested changes may include adjusting window size, adding shading, or modifying the ventilation strategy, because these changes reduce overheating risk.

As our re-modelling process is fast and integrated, clients can resubmit quickly without major project disruption.

Can We Assess Projects at Feasibility Stage?

We provide early-stage thermal reviews during concept or feasibility design.

These assessments are used to explore layout, glazing, and orientation options, because early adjustments are less costly and more flexible.

Since overheating is now a material planning concern in many areas, early reports help reduce risk and support confident submissions.

Can We Work with Architects and Energy Consultants?

We work directly with design teams, consultants, and developers throughout the project.

We coordinate with SAP assessors and M&E consultants, because overheating compliance is often linked to energy strategy and ventilation design.

As overheating risk can affect window sizing, ventilation placement, and building layout, cross-discipline input is essential for compliance.

Can We Deliver Reports Quickly?

Standard delivery is within 3 to 5 working days from receiving plans.

Faster turnaround is available on request, because many projects require compliance documentation under tight deadlines.

Since planning submissions and Building Control approval often depend on thermal reports, early instruction ensures smooth project flow.

What Happens If the Design Fails the Assessment?

We issue a clear explanation of the failure and provide targeted design changes to resolve it.

Since Building Control requires evidence of improvement before approval, the updated design is then re-modelled to confirm compliance.

As the model structure remains in place, turnaround for re-assessment is typically quick and cost-efficient.

Are Overheating Assessments in Eastbourne Required for Conversions or Extensions?

Overheating assessments are required when new habitable spaces are introduced through conversions or extensions.

Since Part O applies to all newly created dwelling spaces, this includes loft conversions and change-of-use schemes.

As these units often have limited natural ventilation, the assessment helps prove that overheating will be adequately controlled.

Are Certain Units More Likely to Fail the Assessment?

Rooms with large glazing areas or restricted ventilation are more prone to overheating.

Top-floor flats, south-facing rooms, and internal bedrooms without cross-flow are especially at risk, because they retain more heat and offer limited natural cooling.

Since these zones are flagged in the model, they are prioritised for design changes where needed.

Can the Assessment Justify Use of Mechanical Cooling?

Mechanical cooling may be permitted only if all passive options are shown to be insufficient.

Since Part O discourages reliance on mechanical solutions, the model must demonstrate failure under natural ventilation before active systems are accepted, 

As planning policy supports low-carbon strategies, passive cooling must always be considered first.

Is an Overheating Assessment in Eastbourne Needed for Prior Approval or Permitted Development?

An overheating assessment in Eastbourne is often required when new dwellings are introduced under permitted development or prior approval routes.

Since these schemes still fall under Building Regulations, it applies to office-to-residential conversions and rooftop extensions.

As many prior approval applications are submitted without mechanical ventilation, natural overheating risk must be assessed in full.

Do All Rooms in the Building Need to Be Modelled?

Only habitable rooms such as bedrooms, living rooms, and open-plan spaces are assessed under Part O.

Non-habitable spaces like hallways and bathrooms are excluded, because compliance focuses on areas where occupants spend extended periods.

As Part O specifies limits for bedrooms and main living areas, the model targets those spaces for analysis.

Can We Provide Local Authority-Specific Reporting?

We tailor all reports to meet both national standards and local validation requirements.

Planning authorities often have specific submission checklists, because thermal comfort is now part of their pre-validation criteria.

As expectations vary between boroughs and regions, we adapt content to satisfy both Part O and local guidance.

Is a Separate Report Needed for Building Control and Planning?

A single overheating report can typically be used for both planning and Building Control, as long as the design remains unchanged.

If layout, window design, or ventilation strategy changes post-approval, a revised assessment may be required.

Since both authorities must verify compliance with Part O, the report must reflect the final approved design.

Does the Assessment Use Future Weather Scenarios?

The assessment uses both current and projected weather files to test overheating risk.

TM59 requires the DSY1 2020s weather file by default, because it reflects anticipated climate conditions for the 2020–2050 period.

As overheating risk is expected to increase, future weather scenarios support climate resilience and long-term compliance.

Are Overheating Assessment Results Used in Energy Strategy?

Overheating assessment results can inform the energy strategy for a development.

Because these elements directly influence both overheating and energy use, they highlight glazing, ventilation, and thermal mass performance.

As coordination across compliance reports is now expected by planners, using shared data improves submission consistency.

Are Separate Assessments Needed for Each Dwelling Type?

Each distinct dwelling layout or orientation may require its own thermal model.

Overheating is assessed at room level, variations in window size, room layout, or ventilation approach affect performance. 

Since Part O focuses on worst-case scenarios, representative units are often selected to streamline the assessment.

Does the Air Permeability Value Affect Overheating Risk?

Air permeability influences how much warm air can escape from the building envelope.

Since restricted air movement reduces natural ventilation, lower air permeability can trap internal heat.

As Part O encourages passive cooling, accurate air permeability assumptions are essential to predict performance correctly.

What Is the Difference Between TM52 and TM59?

TM59 is the methodology used for domestic buildings, while TM52 applies to non-domestic spaces.

As Part O specifically regulates residential thermal comfort, TM59 defines thresholds for bedrooms and living areas.

Since they use different exceedance criteria, the correct method must be applied to suit the building type.

Can Overheating Be an Issue in Winter?

Part O assessments focus on summer performance, but winter conditions can also influence ventilation strategy.

Designs that rely on natural ventilation may struggle in colder months, because occupants are less likely to open windows.

As year-round usability is key to good design, overheating mitigation should also consider seasonal adaptability.

How Do I Book a Part O Assessment in Eastbourne?

Request a free quote from our team at Part O Overheating Assessments in Eastbourne via our online form.

We’ll review your drawings and issue a fixed-fee quote based on unit type, layout, and ventilation strategy.

As compliance with Part O is now a prerequisite for planning validation, early engagement helps keep your project on track.

Get started with Part O Overheating Assessments in East Sussex today.

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