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by Sean Hill on Jul 27, 2023
Our journey in refurbishing London’s historic homes has led us to embrace the EnerPHit refurbishment strategy. This methodology guides us in revitalising older buildings to meet modern efficiency standards, and crucially, aligns with the government’s ‘2050 net-zero‘ carbon emissions target. In this article, we describe how we can upgrade the existing housing stock using EnerPHit methods.
Chapter 1: Understanding the Peculiarities of London’s Historical Housing Stock
London is adorned with a rich tapestry of architectural history – a city where centuries-old Victorian, Georgian, and Edwardian properties rub shoulders with sleek modern buildings. This interweaving of past and present not only enhances the city’s charm but also contributes to its distinct visual and community identity. However, these heritage buildings often underperform in terms of thermal efficiency and are not prepared to meet the challenges of our changing climate.
Queen’s Park House in Queen’s Park, NW London, which included upgrading the existing walls with internal wall insulation.
Chapter 2: Bridging the Past and Future: The Challenge of Energy Efficiency
To reduce our carbon footprint and limit global heating to 1.5 degrees, we must address the deficiencies in these older homes’ thermal design. Often, these buildings are about 3 times less thermally efficient than their contemporary counterparts that meet current building regulations standards. Therefore, it’s crucial to employ modern construction techniques that uphold the character of these historic properties while improving their energy performance.
Chapter 3: Retrofitting London’s Historic Homes with EnerPHit Standards
EnerPHit, a term combining ‘energy’ and the ‘Passive House’ (Passivhaus) concept, offers an effective strategy for overhauling these old structures. Like an insulated flask, an EnerPHit-compliant building retains the right temperature with minimal need for active cooling or heating. Achieving this requires a concerted approach involving well-insulated building envelopes, high-performing windows, efficient ventilation systems, airtight construction, and the elimination of thermal bridges.
Chapter 4: An Architect’s Guide to Implementing EnerPHit Principles
The transition to energy-efficient homes may seem daunting, especially when dealing with older properties. However, with thoughtful planning and a commitment to sustainable design, it’s possible to enhance energy performance while retaining the structure’s unique character. The crucial aspect here is understanding how the five fundamental EnerPHit requirements can be integrated into each project.
The five EnerPHit requirements are:
- High levels of insulation — either internal or external, although internal needs more care in terms of moisture risk
- High-performance triple-glazed windows and external doors
- Careful consideration of window installation
- An airtightness reading of 1.0
- A Mechanical Ventilation with Heat Recovery (MVHR) system
Micro-generation of power, like Solar PVs, can be added to increase the low-energy nature of the home.
Chapter 5: EnerPHit Certification: A Holistic Approach to Refurbishment
EnerPHit certification offers a comprehensive framework for refurbishing existing buildings. It promotes a comprehensive understanding of the built environment, allowing architects to identify ‘easy wins’ for energy savings. The certification process can also be phased to accommodate complex refurbishment projects.
Chapter 6: The Importance of Precise Evaluation and Data Analysis
Before diving into design and construction, it’s essential to thoroughly understand the current state of the building. This understanding relies heavily on data, including quantitative analysis of condensation levels, and thermal imaging, as well as qualitative assessments of structural conditions and notable features. The data gathered will help architects identify suitable solutions to mitigate energy wastage and prevent further decay.
Ice Cream House in Hampstead, North London, has been designed using EnerPHit methods including high levels of insulation, high-performance glazing, airtightness, MVHR, ASHP and Solar PVs.
Chapter 7: Case Study: The Ice Cream House Refurbishment
A practical example of an EnerPHit refurbishment project is our Ice Cream House located in Camden’s conservation areas. The homeowners sought to revamp the 1890s property to suit their contemporary lifestyle. Recognising the opportunity to add long-term environmental value, we applied EnerPHit standards in designing the extensions and internal modifications.
Chapter 8: Tying Old and New: The Role of Material Selection
The Ice Cream House refurbishment not only improved the energy performance but also harmonized old and new elements. The existing building envelope, initially a solid brick skin, was updated with low embodied carbon materials like internal insulation and clay plaster finishes. High-performance double-glazing windows with FSC timber insulated frames were installed for the sash windows, further boosting the house’s energy efficiency.
MVHR ducting at Herbert Paradise in Kensal Rise, NW London
Chapter 9: MVHR and Renewable Energy Integration
To ensure superior indoor air quality, a mechanical ventilation heat recovery (MVHR) system was implemented across the entire property. The MVHR system expels stale air while retaining most of the heat, thereby enhancing energy efficiency. An air source heat pump (ASHP) was also added to satisfy residual energy demands post-renovation as well as Solar Photovoltaic Panels on the rear outrigger roof, helping to edge the property towards a ‘net zero’ state.
An 8 Panel 340W Solar PV System at Ice Cream House in Hampstead, North London
Chapter 10: The Future of Historical Properties: Balancing Heritage and Sustainability
As we look to the future, retrofitting older properties with EnerPHit principles is no longer an option but a necessity. The challenge, however, lies in achieving a delicate balance between preserving the character and heritage of these buildings and introducing the essential elements of modern, energy-efficient design. Just as our predecessors strived for homes that reflected their time, we too must work towards creating homes that will serve the needs of future generations. To accomplish this, architects must commit to sustainable refurbishment practices.
In conclusion, the road to ‘net-zero 2050’ requires a radical rethink of our approach to the existing housing stock. As architects, we have a unique role in shaping this transformation. It’s time we step up and embrace the change, preserving the past while preparing for the future.
Aerial view of Queen’s Park, North West London, with the city centre in the background
Frequently Asked Questions
1. What does ‘net-zero 2050’ mean?
‘Net-zero 2050’ is a target set by many governments, including the UK, to achieve net-zero carbon emissions by the year 2050. This means that by 2050, the amount of greenhouse gases produced will be balanced by the amount removed from the atmosphere, effectively reducing our impact on climate change.
2. What is the EnerPHit refurbishment strategy?
EnerPHit is a strategy for retrofitting existing buildings to drastically reduce their overall energy demand. This is achieved by implementing standards used in Passive House (Passivhaus) construction, which include a well-insulated building envelope, strategic window placement, efficient heat recovery and ventilation systems, an airtight envelope, and avoidance of thermal bridges.
3. What is the Passive House concept?
The Passive House (Passivhaus) concept refers to a rigorous, voluntary standard for energy efficiency in a building. This reduces its ecological footprint, resulting in ultra-low-energy buildings that require little energy for heating or cooling. EnerPHit is the term used when these standards are applied to existing buildings.
4. How can EnerPHit refurbishment address thermal efficiency in older homes?
EnerPHit refurbishment can drastically improve thermal efficiency in older homes by addressing issues such as airtightness, insulation, and ventilation. By implementing EnerPHit principles, these homes can retain warmth during colder months and stay cool during warmer ones, significantly reducing their energy demand and carbon emissions.
5. How is EnerPHit certification achieved?
EnerPHit certification involves a thorough and holistic evaluation of the building. This includes measuring functions like primary energy demand and assessing the performance of components such as windows, doors, and ventilation systems. It also takes into account the building’s existing fabric and allows for phased works to be completed over time.
6. What is the role of data in EnerPHit refurbishments?
Data plays a vital role in understanding a building’s current condition before refurbishments. It allows for a quantitative analysis of aspects like condensation levels, and thermal imaging, as well as qualitative assessments of structural conditions and unique features. This information guides architects towards proven solutions to mitigate energy wastage and further decay.
7. How do materials selection impact EnerPHit refurbishments?
Materials play a critical role in the EnerPHit refurbishment process. The choice of materials can greatly influence the building’s thermal performance, airtightness, and overall sustainability. Using low embodied carbon materials, such as internal wood-fibre insulation, clay plaster and timber structure (as opposed to steel), can help reduce a building’s overall carbon footprint.
8. How does a Mechanical Ventilation Heat Recovery (MVHR) system function?
An MVHR system extracts stale air from a building while retaining most of the heat. The heat exchanger in the system transfers internal heat from outgoing air to incoming fresh external air. This helps maintain indoor air quality, provides a constant fresh air supply, and increases energy efficiency.
9. What is an Air Source Heat Pump (ASHP), and how does it contribute to energy efficiency?
An ASHP is a device that absorbs heat from the outside air and uses it to heat water for space heating. This process continues to work even when the external temperature is as low as -15° C. An ASHP can significantly contribute to a building’s energy efficiency by meeting the residual energy demands after a full renovation.
10. How does the EnerPHit refurbishment strategy balance heritage and sustainability in older buildings?
EnerPHit refurbishment focuses on upgrading a building’s energy performance while preserving its unique characteristics. This involves sensitive upgrades that maintain the building’s aesthetic and historical value, like replacing old components with high-performing replicas, while improving insulation, airtightness, and ventilation for increased energy efficiency. This delicate balance between heritage and sustainability ensures that the historical integrity of the property is maintained while it meets modern-day energy requirements.
If you would like to talk through your project with the team, please do get in touch at mail@risedesignstudio.co.uk or give us a call on 020 3947 5886
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