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What’s an ECO Home and Does it Have EWI?

The term Eco home is fairly general. It does not refer to any one specific house design, but rather an overarching ideal that focuses on sustainable and energy-efficient living. The practice of building Eco homes has never been easier. Initially, the concept was incredibly niche and only achievable with a burgeoning budget. However, advancements in building practices generate more affordable ways to design an Eco home.

One of the most common questions about these innovative dwellings is whether it has EWI. In this blog post, we’ll delve into the world of eco-homes. We will explore EWI, fabric first, Passivhaus, cradle-to-cradle, biophilic design, Earthship Biotecture, green roofs, and living walls. By the end, you’ll have a thorough understanding of what makes an eco-home truly eco-friendly.

Fabric first Eco Home

The fabric-first approach prioritises the building’s envelope (walls, floors, roof) to minimise heat loss and optimise energy efficiency. Insulation, airtightness, and thermal bridging are key components of this strategy. The goal is to create a well-insulated, airtight structure with minimal thermal bridges. As a result, there is a reduced need for heating and cooling systems. EWI is an essential element of fabric first and is often incorporated into eco-homes. EWI wraps the exterior of a building in insulating material, providing an extra layer of thermal protection and decreasing energy consumption.


The Passivhaus standard is a rigorous certification system for energy-efficient homes. Originating in Germany, Passivhaus buildings adhere to strict criteria, focusing on high-performance insulation, airtight construction, thermal bridge-free design, high-performance windows, and mechanical ventilation with heat recovery. These buildings often rely on EWI and other fabric first principles.

High-performance insulation will tend to be thicker than in conventional buildings. As a result, there is less need for energy-intensive heating and cooling systems.

An airtight envelope minimises heat loss through gaps and cracks. The standard requires an airtightness level of 0.6 air changes per hour (ACH) at 50 Pascals pressure.

A Passivhaus design eliminates thermal bridges by carefully planning the building’s details, using continuous insulation, and employing advanced construction techniques.

A Passivhaus design features triple-glazed panes, low-emissivity coatings, and thermally broken or insulated frames. This allows sunlight to warm the interior, while the high-performance glazing and frames prevent heat from escaping.

MVHR systems supply fresh air and exhaust any stale air whilst recovering heat from the outgoing air.

MVHR system diagram
MVHR system – Self-Build

The combination of these principles results in a Passivhaus building that consumes up to 90% less heating and cooling energy than a conventional home. This not only lowers energy bills but also reduces the building’s environmental impact. Additionally, Passivhaus buildings offer a comfortable, healthy living environment with consistent temperatures, excellent indoor air quality, and minimal noise intrusion.

Cradle-to-cradle Eco home

The cradle-to-cradle design emphasises a circular economy, where materials are reused and recycled rather than discarded. This approach considers the entire lifecycle of a building and its materials, seeking to minimise waste and pollution. Eco-homes employing cradle-to-cradle principles often use reclaimed, recycled, or renewable materials, and prioritise deconstruction and recycling at the end of the building’s life.

Biophilic design

Biophilic design connects inhabitants with nature, integrating natural elements like plants, water, and sunlight into the built environment. It’s based on the idea that humans have an innate affinity for nature and that incorporating natural elements can also enhance well-being and productivity. Eco-homes with biophilic designs might also feature green roofs, living walls, indoor gardens, or large windows to maximise natural light.

Living wall on the external of a building
Living walls are designed to support plant life by incorporating a growing medium, such as soil, hydroponics, or a felt-like fabric, and an integrated irrigation system to provide water and nutrients to the plants. Living walls provide insulation, helping to keep buildings cooler in the summer and warmer in the winter.

Earthship Biotecture

An Earthship is a type of eco-home that utilises sustainable materials, passive solar design, and renewable energy sources. Often built from recycled materials like tires, cans, and bottles, Earthships are designed to be self-sufficient, incorporating rainwater harvesting, greywater recycling, and on-site food production. Earthships are a testament to the potential of sustainable, off-grid living.

Features of an Eco home

  1. Energy-efficient design – Eco-homes prioritise energy efficiency through insulation, airtightness, passive solar design, and also the use of renewable energy sources like solar panels or wind turbines.
  2. Sustainable materials – Building materials are chosen for their low environmental impact, durability, and recyclability.
  3. Water conservation – Rainwater harvesting, greywater recycling, and low-flow fixtures help reduce water usage.
  4. Waste reduction – Composting, recycling, and efficient waste management systems which minimise waste production.
  5. Indoor air quality – Eco-homes use materials with low VOC emissions, and also incorporate ventilation systems to promote healthy indoor air.
  6. Green roofs and living walls – These features incorporate vegetation into the building’s structure. These features provide insulation, improve air quality, and also support local biodiversity. Green roofs consist of a layer of plants on the roof while living walls feature vertical gardens on the building’s exterior or interior walls.
  7. Natural lighting – Large windows, skylights, and strategically placed mirrors maximise daylight. This reduces the need for artificial lighting and creates a pleasant atmosphere.
  8. Landscaping – Eco-homes often incorporate native plants and sustainable gardening practices to create low-maintenance, water-efficient landscapes.
  9. Adaptability – Sustainable homes are designed with flexibility in mind, making it easy to modify the space or add extensions as needed, without compromising the building’s efficiency.
  10. Community integration – Eco-homes are often part of larger sustainable developments. This includes shared amenities, public spaces, and a focus on walkability and public transportation.

So how much EWI will you need for an Eco home?

In short, a lot! An Eco home will inherently look towards the Passivhaus standards. Therefore it will require a much thicker thermal envelope which will bring the U-values far lower. Building regulations for retrofits and new builds in the UK state that the U-value has to be at least 0.3W/m²K. Our three insulation boards can achieve this for most substrates at the following thicknesses.

Insulation typeThickness to achieve 0.3W/m²K
Mineral Wool110mm
Kingspan K560mm

Mineral Wool would be the best option for an Eco home due to the sustainable nature of its manufacturing. At EWI Store, we stock Rockwool which is the foremost manufacturer of Mineral Wool. The company ethos focuses heavily on sustainability and circularity:

At ROCKWOOL, we transform volcanic rock into stone wool and our products contribute to address many of society’s biggest climate change challenges, creating new opportunities to enrich modern living and build safer, healthier, and more climate resilient communities. Indeed, stone wool is a versatile natural material with multiple benefits that makes it ideal for applications in buildings, industry, transportation, horticulture, and water management. 

We pursue a fact-based, auditable approach backed up by third-party references and methodologies to document progress in maximising our products’ positive impact (handprint) and minimising the impact of our operations (footprint). 


Our products can be easily removed when a building is renovated, or demolished and recycled back into new products. In fact, stone wool can be recycled again and again into new stone wool. This is an important element of a “circular” business model – another way you can be a part of our vision for sustainable cities of the future.


If you have any other questions about Eco Homes and EWI’s role in them, leave us a comment below!


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