How to Plan a Deep Retrofit in Dublin: From BER Assessment to Energy Upgrades

 Energy efficiency has moved to the top of the agenda for Dublin homeowners. Between rising energy costs, increasing environmental awareness, and significant government grant support through the SEAI, a deep retrofit has become one of the most impactful investments a homeowner can make. But what does a deep retrofit actually involve, where do you start, and how do you ensure the project delivers the results it promises?

This guide walks through every stage of a residential deep retrofit in Dublin, from the initial BER assessment through to completion, so homeowners can approach the process with confidence and clarity.

What Is a Deep Retrofit?

A deep retrofit is a comprehensive programme of energy upgrade works that transforms a poorly performing home into a highly energy-efficient one. Unlike a single upgrade, such as installing a new boiler or adding attic insulation, a deep retrofit addresses the home as an integrated energy system, improving the building fabric, the heating system, the ventilation strategy, and the renewable energy provision in a coordinated and sequenced way.

The target outcome for a deep retrofit is typically a BER of B2 or above, which qualifies the project for the SEAI's National Home Energy Upgrade Scheme. Many homeowners go further, targeting an A-rated home or achieving passive house retrofit standard, which represents the highest level of energy performance achievable through a retrofit project.

The BER Assessment: Your Starting Point

Every deep retrofit journey begins with a BER assessment carried out by a registered BER assessor. The assessment evaluates the existing energy performance of the home, taking into account:

•         The age, type, and construction of the building

•         The current level of insulation in the roof, walls, and floors

•         The type and condition of windows and doors

•         The heating system, hot water system, and any renewable energy provision

•         The ventilation strategy (or lack of one)

•         Air permeability and draughtiness of the building fabric

The result is a BER certificate and a detailed advisory report. This report forms the foundation for your retrofit plan, identifying where the greatest energy losses occur and which upgrade measures will deliver the most benefit.

For homeowners considering a passive house retrofit, a more detailed energy modelling exercise using software such as PHPP (Passive House Planning Package) will typically be carried out alongside the standard BER assessment.

Understanding Your Retrofit Pathway

One of the most important principles of a successful deep retrofit is sequencing. Energy upgrade measures interact with each other, and the order in which they are carried out matters significantly. As a general rule, the following sequence is recommended:

1.         Fabric first: Reduce heat loss through the building envelope by upgrading insulation in the roof, external walls, and ground floor. This is the most impactful step and should be completed before the heating system is upgraded.

2.         Airtightness: Improve the airtightness of the building fabric to reduce uncontrolled heat loss through gaps and cracks. This step is closely linked to the fabric works above.

3.         Ventilation: Once a building is made significantly more airtight, mechanical ventilation with heat recovery (MVHR) is typically required to maintain healthy indoor air quality.

4.         Heating system: With the heat demand of the building substantially reduced, the existing heating system can be downsized and upgraded. A heat pump is the most common choice for a deep retrofit.

5.         Renewables: Solar PV panels or solar thermal can be added to generate on-site electricity or hot water, further reducing energy bills and carbon emissions.

Key Upgrade Measures Explained

External Wall Insulation (EWI)

External wall insulation involves fixing insulation boards to the outside of the existing walls and rendering or cladding over them. It is the most effective method of insulating solid wall properties, which make up a significant proportion of older Dublin housing stock. EWI does alter the external appearance of a building and may require planning permission for certain property types.

Internal Wall Insulation (IWI)

Where external insulation is not feasible, internal insulation can be applied to the inner face of external walls. Internal insulation involves some loss of floor area and requires careful detailing to avoid cold bridging and moisture issues.

Roof and Attic Insulation

Heat rises. Upgrading roof or attic insulation is consistently one of the most cost-effective upgrade measures available. For an accessible attic, blown or laid insulation to a depth of 300mm or more brings the roof to current standards.

Floor Insulation

Heat loss through ground floors is often underestimated. For suspended timber floors, insulation can be fitted between the joists. For solid concrete floors, insulation is laid on top of the existing slab before a new screed is poured.

Windows and Doors

Upgrading to high-performance triple-glazed windows and well-insulated external doors significantly reduces heat loss through openings. In a deep retrofit targeting passive house standard, window and door selection is particularly important, as the frames, glazing, and installation method all affect the overall energy performance and airtightness of the building envelope.

Mechanical Ventilation with Heat Recovery (MVHR)

A well-sealed home needs a controlled ventilation strategy to maintain healthy indoor air quality. MVHR systems supply fresh filtered air to living and sleeping areas while extracting stale air from kitchens and bathrooms. Critically, they recover up to 90% of the heat in the outgoing air. This is a core element of any passive house retrofit and is increasingly used in standard deep retrofit projects too.

Heat Pumps

Air-to-water heat pumps are the most common heating system upgrade in a deep retrofit. They extract heat energy from outdoor air and use it to heat water for space heating and domestic hot water. Heat pumps perform best in a well-insulated building with low-temperature heat emitters such as underfloor heating or large-format radiators, which is why fabric upgrades should precede heating system changes.

SEAI Grants and Supports for Dublin Homeowners

The SEAI administers a range of grants for homeowners undertaking energy upgrades. The National Home Energy Upgrade Scheme is the most comprehensive, offering grant support for a full deep retrofit delivered by a registered SEAI One Stop Shop provider. Individual measure grants are also available for homeowners who wish to upgrade specific elements such as insulation, heating systems, or solar PV.

Grant levels, eligibility criteria, and application processes are updated by the SEAI from time to time, so it is always advisable to check the current SEAI website for the most up-to-date information. A registered retrofit contractor in Dublin will be familiar with the grant landscape and can advise on which supports your project may be eligible for.

Choosing a Deep Retrofit Contractor in Dublin

The quality of a deep retrofit is directly linked to the skill and experience of the team carrying it out. When selecting a contractor for a deep retrofit in Dublin, look for:

•         Registration with the SEAI and familiarity with the National Home Energy Upgrade Scheme

•         Experience in the specific upgrade measures required for your property type

•         References from previous retrofit projects of comparable scale

•         A willingness to carry out a thorough pre-works assessment and provide a detailed specification before quoting

•         An understanding of the sequencing principles outlined above

Stonebuilders specialises in passive house retrofit and comprehensive deep retrofit projects across Dublin, delivering measurable improvements in energy performance and occupant comfort.

Frequently Asked Questions

What BER rating can be achieved through a deep retrofit?

Most deep retrofit projects target a BER of B2 or above, which is the minimum required to qualify for the SEAI's National Home Energy Upgrade Scheme. Many homeowners choose to aim higher, targeting A3, A2, or A1. A passive house retrofit, which applies the rigorous Passivhaus standard to a refurbishment project, can achieve the highest levels of energy performance, with extremely low space heating demand and exceptional indoor comfort.

How disruptive is a deep retrofit to daily life?

A full deep retrofit is a significant project and will cause disruption, particularly if insulation works involve internal wall treatments, floor works, or MVHR ductwork installation throughout the home. Many homeowners choose to move out temporarily during the most intensive phase of works. Your retrofit contractor should provide a detailed programme in advance.

Is a deep retrofit worth it for an older Dublin property?

Yes, in most cases. Older Dublin properties, particularly those built before the 1980s, typically have poor thermal performance, high energy bills, and significant carbon footprints. A deep retrofit can dramatically reduce energy consumption, lower bills, improve thermal comfort, eliminate draughts and dampness, and contribute to the long-term preservation of the building fabric.

Does a deep retrofit require planning permission?

Most energy upgrade measures do not require planning permission. However, external wall insulation that alters the external appearance of a property may require planning permission, particularly for terraced houses or properties in Architectural Conservation Areas. Your retrofit contractor or architect will advise on the planning position for your specific project.

What is the difference between a standard retrofit and a passive house retrofit?

A standard retrofit improves the energy performance of a home, typically targeting a BER of B2 or above. A passive house retrofit applies the internationally recognised Passivhaus standard to a refurbishment project, targeting a verified space heating demand of no more than 25 kWh per square metre per year. It involves a higher level of insulation, superior airtightness, high-performance windows, and MVHR, verified by Passivhaus Institute-certified modelling software.