Energy Performance of Modular Buildings in the UK
Energy performance is now a top priority in UK construction. Because of this, every KC Modular building achieves an EPC A rating as standard.
As a result, you get lower energy bills and full Part L 2021 compliance from day one. Furthermore, our U-values are among the lowest in the modular sector.
What Is Energy Performance in Modular Buildings?
Energy performance measures how well a building retains heat and uses energy. In other words, it shows how much energy you need to keep the building comfortable.
Because modular buildings are factory-made, insulation is installed with precision. As a result, energy performance is more consistent than in traditional construction.
Three Key Metrics That Define Performance
Energy performance depends on three main factors. Furthermore, each one is measured and certified independently before your building leaves the factory.
Thermal Transmittance
This measures heat loss through walls, roof, and floor. Lower numbers mean better insulation. For example, our walls achieve 0.16 W/m²K — well below Part L limits.
Airtightness
This measures how much air leaks through the building envelope. Our buildings achieve 1.57 m³/(h.m²). Consequently, heat loss from draughts is almost eliminated.
Energy Performance Certificate
This is the overall energy score from A to G. KC Modular buildings achieve EPC A as standard. As a result, running costs are significantly lower than average buildings.
Why Energy Performance Matters Now More Than Ever
Energy costs have risen sharply in recent years. Because of this, building owners need structures that minimise heating and cooling demand.
Furthermore, Part L 2021 introduced stricter energy targets for all new buildings. Therefore, choosing a high-performance modular building is both a legal requirement and a smart financial decision.
In addition, energy efficient buildings have higher resale and rental values. Consequently, investing in better thermal performance pays for itself over time.
Part L 2021 Compliance
Part L of the Building Regulations sets energy efficiency standards for all new buildings. Because the 2021 update raised the bar significantly, many builders struggle to comply.
However, KC Modular buildings already exceed Part L 2021 requirements. As a result, you get future-proof energy performance without any design compromises.
What Part L 2021 Requires
The 2021 update introduced four key changes. Furthermore, these changes apply to both new builds and major renovations. Here is what you need to know.
Lower U-Value Targets
Part L 2021 requires lower U-values for walls, roofs, and floors. In other words, buildings must retain more heat than before.
Because KC Modular uses 200mm insulated panels, our U-values already beat these targets. Consequently, compliance is built in from the design stage.
Improved Airtightness
Buildings must now achieve better airtightness scores. This reduces heat loss from uncontrolled air leakage.
Our factory-sealed construction achieves 1.57 m³/(h.m²). As a result, this is well below the Part L threshold. Furthermore, every building is pressure-tested before handover.
Better Window Performance
Windows must now achieve lower U-values. Therefore, single and basic double glazing no longer meet the standard.
KC Modular installs triple-glazed windows rated at 0.5-0.7 W/m²K. As a result, our glazing exceeds Part L 2021 by a significant margin.
Reduced Carbon Emissions
Part L 2021 targets a 31% reduction in carbon emissions compared to 2013 standards. This is a major step towards the 2025 Future Homes Standard.
Because our buildings achieve EPC A ratings, carbon emissions are already well below the new limits. In addition, our factory process reduces construction waste by 90%.
U-Value Breakdown by Component
U-values measure heat loss through each building element. Lower numbers mean better insulation. Because KC Modular uses premium materials, our U-values lead the sector.
Furthermore, every U-value is independently calculated and certified. As a result, you can trust the numbers on your specification sheet.
KC Modular U-Values at a Glance
Here are the U-values for each major building element. In addition, each card shows the material responsible for that performance.
External Walls
200mm KINGSPAN QuadCore panels with PIR Thermano insulation.
As a result, heat loss through walls is minimal. Furthermore, this beats Part L by over 25%.
Roof
Insulated roof cassette with Protan membrane and 300mm Rockwool.
Consequently, roof heat loss is almost eliminated. In addition, the Protan membrane provides a 30-year weatherproof guarantee.
Floor
Heavy-gauge galvanised steel floor with PIR insulation and SPC Rocko baseboard.
Therefore, ground-level heat loss is kept to a minimum. Also, the steel base provides long-term structural durability.
Windows
Triple-glazed aluminium or UPVC frames with argon-filled cavities.
As a result, glazing performance matches the insulated walls. Furthermore, G-values are optimised for solar heat gain.
How We Compare to Part L Requirements
The table below compares KC Modular U-values against Part L 2021 maximum limits. Because we exceed every target, compliance is guaranteed.
| Element | KC Modular | Part L 2021 Limit | Performance |
|---|---|---|---|
| External Walls | 0.16-0.18 W/m²K | 0.26 W/m²K | 38% Better |
| Roof | 0.11 W/m²K | 0.16 W/m²K | 31% Better |
| Floor | 0.11 W/m²K | 0.18 W/m²K | 39% Better |
| Windows | 0.5-0.7 W/m²K | 1.6 W/m²K | 69% Better |
| Air Permeability | 1.57 m³/(h.m²) | 8.0 m³/(h.m²) | 80% Better |
Insulation and Materials That Deliver
Energy performance starts with the right materials. Because we use premium insulation throughout, every building element contributes to the overall A rating.
Furthermore, all materials are sourced from certified manufacturers. As a result, quality and performance are guaranteed for the life of the building.
Wall and Panel Insulation
Our walls use a combination of rigid board and mineral wool insulation. Consequently, thermal bridging is minimised across the entire envelope.
200mm
KINGSPAN QuadCore Panels
These panels combine structural strength with outstanding insulation. In addition, they are lightweight and fast to install.
Because QuadCore has a lower lambda value than standard PIR, thinner panels achieve better U-values. As a result, you get more internal floor space.
300mm
Rockwool and Isover Multimax
We use mineral wool for acoustic and thermal performance in internal walls and ceilings. Furthermore, Rockwool is non-combustible and adds fire protection.
Consequently, you get both energy efficiency and sound insulation in one material. Also, mineral wool does not degrade over time.
Glazing and Window Systems
Windows are often the weakest point for energy loss. However, KC Modular uses triple glazing as standard. Therefore, our windows perform closer to insulated walls than typical glazing.
Glazed
Aluminium Frame Windows
These achieve U-values of 0.5-0.7 W/m²K. In addition, aluminium frames are durable and low-maintenance.
Because argon gas fills the cavities, heat transfer through the glass is significantly reduced. As a result, condensation risk is also lower.
Option
UPVC Frame Windows
UPVC frames offer excellent thermal performance at a lower cost. Furthermore, they require no painting or surface treatment.
As a result, UPVC is ideal for budget-conscious projects. Also, triple-glazed UPVC achieves the same U-values as aluminium alternatives.
Roof and Floor Systems
Heat rises, so roof insulation is critical. In addition, ground-level heat loss through floors can account for up to 15% of total energy waste. Because of this, we insulate both to the highest standard.
Roof
Insulated Roof Cassette
Our roof system combines 300mm Rockwool with a Protan single-ply membrane. Consequently, the roof achieves a U-value of just 0.11 W/m²K.
Furthermore, the Protan membrane carries a 30-year guarantee. As a result, you get long-term weatherproofing and thermal performance in one system.
Floor
Insulated Steel Floor
Our floors use heavy-gauge galvanised steel with PIR insulation. Also, SPC Rocko baseboard provides a durable, moisture-resistant surface layer.
Because the floor is fully sealed at the factory, there are no gaps or cold bridges. Therefore, floor U-values match the roof at 0.11 W/m²K.
Energy Savings and Running Costs
Better energy performance means lower bills. Because KC Modular buildings achieve EPC A ratings, running costs are a fraction of older or poorly insulated buildings.
Furthermore, energy savings compound year after year. As a result, the total cost of ownership is significantly lower over the building's 50 to 75 year lifespan.
The Numbers That Matter
Here are three key figures that show the real-world impact of our energy performance. In addition, these numbers are based on independently verified data.
Reduced Heat Loss
Because our U-values are 30-80% better than Part L limits, heating demand drops dramatically. Consequently, you use less energy to stay comfortable.
Superior Airtightness
Our air permeability of 1.57 m³/(h.m²) is 80% better than the Part L limit. As a result, draughts are eliminated and heating systems work more efficiently.
Factory Efficiency
Because 90% of construction happens in our factory, material waste is reduced by 90%. Furthermore, this lowers the carbon footprint of every project.
Long-Term Financial Benefits
Energy efficient buildings are not just cheaper to run. They also hold higher resale and rental values. Therefore, better energy performance is a smart investment.
In addition, many lenders now offer green finance incentives for A-rated buildings. Consequently, your financing costs may also be lower.
Future-Proofed for the 2025 Future Homes Standard
The UK government plans to introduce the Future Homes Standard in 2025. This will require even stricter energy performance from all new buildings.
Because KC Modular already exceeds Part L 2021 by a wide margin, our buildings are well positioned for these future requirements. As a result, you avoid costly retrofits down the line.
Energy Performance FAQ
Quick answers to the most common questions about energy performance in modular buildings. Furthermore, each answer explains how KC Modular meets the requirement.
All KC Modular buildings achieve an EPC A rating as standard. This is the highest energy performance certificate rating available.
As a result, running costs are significantly lower than buildings rated B or below. Furthermore, A-rated buildings attract higher resale and rental values.
Our walls achieve 0.16-0.18 W/m²K. Roofs and floors reach 0.11 W/m²K. Windows achieve 0.5-0.7 W/m²K.
As a result, these figures beat Part L 2021 requirements by 30-80%. In addition, every U-value is independently calculated and certified.
Yes. All KC Modular buildings exceed Part L 2021 requirements. Because we use 200mm insulated panels and triple glazing, compliance is built in from the design stage.
Furthermore, every building is pressure-tested before handover. Consequently, you receive certified proof of compliance with every project.
KC Modular buildings achieve air permeability of 1.57 m³/(h.m²). This is 80% better than the Part L maximum of 8.0 m³/(h.m²).
Because construction happens in a controlled factory, seals and joints are more precise. As a result, draughts and uncontrolled air leakage are virtually eliminated.
We use KINGSPAN QuadCore panels for external walls. Rockwool and Isover Multimax handle internal insulation. PIR Thermano insulates the floors.
As a result, every building element contributes to the overall A rating. Furthermore, all insulation materials are certified and independently tested.
Yes. Because 90% of construction happens in a factory, insulation installation is more precise and consistent.
Furthermore, factory-sealed joints eliminate the air gaps common in traditional on-site construction. As a result, modular buildings typically outperform traditional builds on energy efficiency.
Yes. Triple glazing is standard on all KC Modular buildings. Our windows achieve U-values of 0.5-0.7 W/m²K with argon-filled cavities.
Consequently, this is well below the Part L 2021 limit of 1.6 W/m²K. In addition, G-values are optimised to balance solar heat gain with insulation.
Our buildings already exceed Part L 2021 by a wide margin. Because the Future Homes Standard builds on Part L, our current specifications are well positioned.
As a result, you avoid costly retrofits in the future. Furthermore, investing in high energy performance now protects your building's value long-term.
Get EPC A as Standard.
Not as an Upgrade.
Every KC Modular building beats Part L 2021 requirements. Because of this, you pay less to heat and run your building. In addition, your asset holds more value over time.
We build in a controlled factory. As a result, we achieve air permeability of just 1.57 m³/(h.m²). That is 80% better than the legal maximum. So there are no surprises at handover.
Let’s Talk About Your Next Project
You might need a single office module. Or you might need a full multi-building programme. Either way, we will give you a clear specification and honest quotation. There is no obligation and no pressure.
Final specification subject to engineering design and site conditions. U-values and energy ratings reflect standard KC Modular specifications. Quotations exclude groundworks, utility connections, external works, and VAT unless stated.