ROBBIE COUSINS writes about how the Irish Heritage Trust in partnership with Poetry Ireland/ Éigse Eireann, and a specialist team, delivered an A3 BER rating, sustainable energy solutions and seamless universal access in the 300-year-old Georgian townhouse at No 11 Parnell Square, Dublin.
The official opening of No 11 Parnell Square in early 2026 marked a transformative chapter for Ireland’s architectural and cultural landscape. Following a comprehensive €5.5m conservation and refurbishment project led by McCullough Mulvin Architects, the early 18th-century Georgian townhouse now serves as a shared headquarters for Poetry Ireland/Éigse Éireann, the Irish Heritage Trust and the Irish Landmark Trust.
While celebrated for establishing a new civic home for literature and heritage – housing facilities such as the new Seamus Heaney Poetry Library and the historic former Dublin County Council Chamber – the true triumph of No 11 Parnell Square lies in its engineering and technical execution. Balancing historical integrity with 21st-century environmental standards, the project team achieved an exceptional A3 Building Energy Rating (BER). This case study explores how rigorous conservation principles and modern sustainability requirements were integrated into a unified building strategy, demonstrating that historic urban assets can meet the highest operational, accessibility, and environmental standards without losing their historic soul.
PROJECT OVERVIEW
Originally constructed around 300 years ago, No 11 Parnell Square is a Protected Structure of significant historical, architectural and cultural importance. Over its long history, the townhouse has served multiple functions, notably at one stage housing the chamber of Dublin County Council.
The core brief required converting this grand townhouse into a functional, accessible headquarters and public amenity for three distinct organisations, each with unique operational, public and archival requirements. Bridging these needs while upholding strict conservation standards demanded a multi-layered design strategy that transformed key heritage spaces into versatile public venues, administrative suites, and secure archival facilities.
PROCUREMENT STRATEGY
Because the primary funding stemmed from the Urban Regeneration and Development Fund (URDF), the project strictly adhered to Irish public procurement rules. Procurement was conducted via the eTenders portal using a Most Economically Advantageous Tender (MEAT) evaluation. The chosen contract vehicle was the Public Works Contract CF5 (Employer Design), the standard for public projects in which design is fully developed by the employer’s consultant team.
CF5 kept design risk with the employer side, which was essential given the sensitive nature of McCullough Mulvin’s conservation specifications. Bourke Builders was awarded the contract
CASH FLOW AND REPORTING STANDARDS
Public and philanthropic funding requires high standards of governance. Brendan Merry & Partners (BMP) acted as quantity surveyor and employer representative, issuing 17 comprehensive monthly cost reports over a 21-month period. These reports were reviewed by the project steering committee and made available to funding bodies. Monthly interim payment recommendations formed the formal drawdown profile, creating an auditable paper trail.
PROJECT GOVERNANCE
From the outset, a project Steering Committee was established consisting of representatives of the Stakeholders: Irish Heritage Trust, Poetry Ireland/Éigse Éireann and the government department. At monthly meetings, the Steering Committee were appraised of progress on site. The contingency was treated as a strictly controlled project resource. Every variation required initial assessment by BMP and formal authorisation by the steering committee before instructions were issued to the site. Through such strict control, the project reached Substantial Completion in March 2026 within its overall planned budget and timeline.
CONSERVATION IN PRACTICE: MATERIALS, FABRIC AND HERITAGE PRESERVATION
Conservation at No 11 Parnell Square focused on retaining as much original fabric as possible, using traditional materials, and making all modern interventions reversible.
Envelope works: roof and brickwork
Executing works on a tight urban footprint along Parnell Square presented logistical constraints. The envelope works involved two primary conservation tasks:
– Roof replacement: Removing modern overhead alterations and re-roofing using traditional slate, lead flashing, and timber details.
– Façade repointing: Repairing the red-brick front elevation using lime-based mortars matched in colour, aggregate, and joint profile to the original Georgian brickwork.
Working directly adjacent to busy public footpaths and live urban traffic required careful scaffold management, dust containment, and material deliveries.
Off-site restoration of Victorian furniture
The Council Chamber and Secretary’s Office contain important Victorian furniture, including the original boardroom table and seating. To prevent site damage during major structural works, these items were tendered separately from the main contract as a specialist subcontract package.
A specialist conservator removed the furniture to an off-site workshop and the restored pieces were re-installed in the Council Chamber late in the construction programme.
SUSTAINABILITY AND ENVIRONMENTAL PERFORMANCE: THE PATH TO A3 BER
Achieving an A3 BER in a 300-year-old Georgian Protected Structure is a notable engineering feat. Standard modern builds achieve A-ratings using thick external wall insulation and airtight vapour barriers. However, applying impermeable materials to historic solid-brick walls traps moisture, causing interstitial condensation, timber rot and masonry spalling.
To deliver low operational carbon while protecting the building’s fabric, M&E consultants JV Tierney and mechanical sub-contractors Phoenix Mechanical adopted a fabric-first strategy using breathable materials:
– Breathable mineral wool insulation – Installed within internal void spaces and ceiling zones. Mineral wool allows moisture vapour to pass through the wall assembly, preventing trapped dampness.
– Window restorations – Original timber sash windows were refurbished, reweighted, and draft-sealed. Improved glazing was integrated into the sashes to cut heat loss while preserving original profiles.
– Passive measures & LED – Natural ventilation strategies were retained, and 100% high-efficiency LED lighting was specified throughout.
BIVALENT HEATING SYSTEM
At the heart of the building’s mechanical system is a bivalent heating configuration designed to balance low carbon emissions with reliable heating during peak cold periods. Supplied by Hevac, the system pairs two distinct heat sources:
– Primary Load (Air-source heat pumps) – High-efficiency Clivet air-source heat pumps (ASHPs) handle the steady-state base heating demand for most of the year and preheat domestic hot water.
– Peak Load (Condensing gas boilers) – Two De Dietrich condensing gas boilers, arranged in a cascade kit, step in during extreme winter temperatures when outdoor air heat pump efficiency drops.
BUILDING MANAGEMENT SYSTEM
This system is managed by an integrated building management system (BMS) and sub-metering network that optimises plant operation based on outdoor temperatures, room occupancy and live energy tracking. By allowing heat pumps to supply baseload heating, the bivalent setup delivers significant carbon and operational savings compared to traditional gas systems, while providing the high water temperatures needed for traditional radiator circuits.
RELATIONSHIP BETWEEN CONSERVATION AND SUSTAINABILITY
The project highlights how heritage conservation and modern environmental performance can support one another. Rather than treating sustainability as an additive layer, the design team used heritage constraints to drive cleaner engineering solutions.
RESOLVING COUNCIL CHAMBER COMPARTMENTATION AND FIREPROOFING
The clearest example of this dynamic occurred in the first-floor Council Chamber. The room features two competing historic elements: a delicate timber parquet floor on the first floor and an intricate Victorian low-relief fibrous plaster ceiling (featuring neo-Tudor pierced quatrefoils and a classical cornice) directly below it on the ground floor.
Standard floor compartmentation involves lifting floorboards from above, clearing original pugging, and fitting fire insulation between the joists. However, lifting the historic parquet floor was ruled out due to the risk of irreversible damage.
At the tender stage, the design included an active water-mist suppression system to protect the floor void. However, during early site works in mid-2025, technical reviews highlighted two major issues with this approach:
– The required water storage tanks, pump sets and pipework would consume scarce plant space, competing directly with the new M&E and heat pump equipment.
– Distributing pressurised water pipes above fragile plaster ceilings posed a risk of leaks to the historic fabric.
The design team pivoted to a traditional, structural alternative. They carefully removed some damaged lath and plaster ceiling on the ground floor, fitted fire-rated board and insulation between the timber joists from below, and reinstated the ceiling using traditional lath-and-plaster techniques with original salvaged laths.
This bottom-up method had multiple benefits:
– The parquet floor remained completely untouched
– It achieved full passive fire compartmentation between floor levels without relying on mechanical pumps
– It freed up plant space needed for the bivalent heat pump infrastructure
– It yielded a significant cost reduction compared to the misting system. The net savings allowed other conservation works to be completed that otherwise would not have proceeded.
REVERSIBLE SERVICES ROUTING AND UNIVERSAL ACCESSIBILITY
Introducing modern mechanical, electrical and plumbing services into low-relief plaster rooms required non-destructive routing strategies. All M&E routes used existing voids identified during pre-construction surveys. The guiding principle was full reversibility, ensuring that any modern cable, pipe or LED fixture can be removed in the future without damaging the original plaster or woodwork.
Achieving universal accessibility presented similar challenges. Historically, Georgian townhouses were designed with steps at entry points and narrow multi-story layouts. Main contractor Bourke Builders installed two lift systems:
– A primary internal lift running through non-historic secondary voids to serve all four floors, including the Seamus Heaney Poetry Library, and
– An external platform lift to the front lightwell to provide step-free access from street level.
These circulation upgrades were approved under alternative compliance pathways for Protected Structures. This provided step-free public access while leaving the original timber-lined chambers, decorative joinery, and floor surfaces intact.
TECHNICAL PERFORMANCE AND KEY TAKEAWAYS
The delivery of No 11 Parnell Square offers practical lessons for the refurbishment of complex historic buildings:
– Embrace a bivalent heating strategy: Pairing air-source heat pumps with condensing gas boilers allows heat pumps to meet base loads while boilers handle extreme peaks. This delivers substantial carbon emission reductions without over-sizing equipment in historic plant rooms.
– Prioritise passive fabric-first interventions: Use vapour-permeable, natural materials, such as mineral wool insulation and slimline secondary glazing, to boost energy efficiency while allowing walls to breathe and preventing dampness.
– Leverage conservation to solve engineering constraints: Passive, traditional methods, such as reinstating lath and plaster ceilings from below, can often meet fire safety needs more cost-effectively and reliably than complex active mechanical systems.
– Ensure rigorous monthly financial governance: Maintain detailed monthly cost reports across mixed public and philanthropic funding streams to prevent budget surprises, protect contractor cash flow, and satisfy funding compliance requirements.
IN CONCLUSION
The successful revival of No 11 Parnell Square shows that heritage conservation and modern environmental performance can work hand in hand. By combining a fabric-first approach with a bivalent heat pump system, McCullough Mulvin Architects, Brendan Merry & Partners, Bourke Builders, and JV Tierney transformed a 300-year-old Georgian townhouse into an energy-efficient (A3 BER), fully accessible public facility.
As Ireland works toward urban regeneration and carbon reduction goals, No 11 Parnell Square provides a useful template. It demonstrates that historic buildings do not need to be exempted from modern performance standards. Through careful design, traditional craftsmanship, and flexible engineering, historic structures can be adapted to serve future generations while retaining their original character.
PROJECT TEAM
Client: Irish Heritage Trust in partnership with Poetry Ireland/Éigse Eireann, (Head of PMO: Peter Kirk)
Lead Architect: McCullough Mulvin Architects
Quantity Surveyor and Employer Representative: Brendan Merry & Partners
Main Contractor: Bourke Builders
M&E Engineering Contractor: JV Tierney
Mechanical Subcontractor: Phoenix Mechanical