nZEB Houses & Buildings – The Thermohouse Solution

What is nZEB?

NZEB or ‘Nearly Zero Energy Buildings’, is a building standard which applies to all new buildings occupied after the 31st December 2020.

NZEB means a building that has a very high energy performance where the nearly zero or very low amount of energy required should be covered to a very significant extent by energy from renewable sources including energy from renewable sources produced on-site or nearby, as per Part L 2019.

What is the Thermohouse nZEB Solution?

At Thermohouse, we manufacture, supply and install a building solution which is both nZEB and Part L 2019 compliant.

The Thermohouse nZEB solution is a complete energy efficient building envelope, featuring superior airtightness, high levels of insulation and minimal thermal bridging.

The Thermohouse Solution comprises of 4 components which  interlock to form a complete structure:

  1. Thermowall
  2. Thermofloor
  3. Thermoroof
  4. Thermoboard

In addition, our nZEB houses use far less energy than traditional builds, increasing comfort and lowering energy bills! Average Energy Usage: 35kWh/m²/yr

1. Superior Airtightness – Far in excess of nZEB requirements

Typical Areas of Air Leakage

The Thermohouse Solution

A. Interlocking Thermoroof panels prevent air leakage through the roof


B. Thermowall and Thermofloor modules are designed to interlock to form the monolithic concrete structure which is fully wrapped in insulation


C. Thermowall window reveal blocks seal windows to the structure


D. Monolithic concrete structure prevents air leakage you would typically see through masonry joints in traditional construction

nZEB  & Part L – Air Permeability 


Thermohouse – Air Permeability


2. High Levels of Insulation

Fabric Element Part L 2019 U-Value Thermohouse U-Value
Pitch Roof 0.16 0.15
Flat Roof 0.20 0.15
Walls 0.18 0.15 – 0.10
Ground Floor 0.18 0.18 – 0.12

3. Minimal Thermal Bridging

Our building system has been designed to avoid excessive heat loss and condensation issues.

As the system’s insulated components interlock there is a continuity of insulation which wraps the entire monolithic concrete structure, preventing thermal bridging at key junctions.


For further details on our thermal performance, please review our report devised by the BRE, aswell as PSI document.

Please note that our summary of certified psi-values is for use in SAP/DEAP/Y-factor calculations. All calculations carried out in accordance with IS EN ISO 10211:2007 and BR497:2016.

Part L 2019: Further Information on nZEB

Technical Guidance Document L:

Conservation of Fuel and Energy

Dwellings (2019)


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