Embracing constraints in a Fife Passivhaus

Architect & PHT member Kirsty Maguire wanted to build her own home ever since she was little. With several Passivhaus projects under her belt, including the award-winning New Farmhouse and several others, she was ready to embrace a challenge for her own home.

After years of searching for the right location, Kirsty found a site in her local village. Nestled on a steep rocky, north-facing slope in Newport-on-Tay, the site had been dismissed by many as too difficult to develop. But for an experienced Passivhaus designer, it was the perfect opportunity to prove that even the most constrained locations can deliver an exceptional home.

The Silver House Passivhaus works with its landscape. Clad in shimmering metallic and natural larch, the home reflects the ever-changing light of the River Tay, while its considered Passivhaus design ensures year-round warmth and ultra-low energy use. More than just a residence and convincing office space for potential clients, it stands as a testament to how Passivhaus design can transform even the most challenging sites into thriving, comfortable homes.

Key stats

Construction: Timber frame with raft foundations and insulated retaining walls
TFA: 137 m²
Build start date: 2020
Completed: 2022
Certified: Passivhaus Classic - certification pending

The Silver House - Passivhaus Classic - Image © Kim Cessford

Silver House Passivhaus, Kirsty Maguire quote: If you don't have the perfect site you can still absolutley build to Passivhaus. I always wanted to build my own home ever since I was little. When this site came up it was perfect for me. Its slope made the design and build a bit of a challenge but it was worth it

Construction

The house's construction was shaped by site constraints and material choices. A timber-stud structure with external wood fibre insulation was chosen for its breathability and low embodied carbon. Below ground, a concrete block retaining wall was insulated to maintain thermal efficiency. Due to space limitations, off-site manufacturing was not feasible. Every component was manually carried onto the site, requiring careful planning.

The home integrates low-carbon materials, using natural, breathable insulation that enhances thermal mass and comfort. Recycled vegetable oil was used to coat the stainless-steel cladding, ensuring durability and future recyclability. Stone from the existing boundary wall was repurposed in gabions, and additional reclaimed stone was sourced locally.

See more on Instagram @house_on_a_hill_passivhaus

Overheating was addressed through careful glazing optimisation using the Passivhaus Planning Package (PHPP), eliminating the need for external shading. The north-facing slope played a key role in this strategy, allowing winter sun to warm the home while preventing overheating in summer.

U-values

Roof: 0.1W/m²K

Timber I beam with wood fibre insulation infill, and woodfibre external insulation layer

Wall: 0.12W/m²K above ground & 0.15/m2K below ground

Retaining: Insulated concrete block

Above ground: Timber stud with wood fibre insulation infill, and woodfibre external insulation layer

Floor: 0.13W/m²K

Insulated concrete raft

Building performance

Designed energy performance
Airtightness n₅₀ (≤ 0.6ACH @ 50 Pa)	0.31 @ 50 Pa
Space Heating Demand (≤ 15 kWh/m².a)	14 kWh/m².a
Heating Load (≤ 10 W/m²)	10 W/m²
Primary Energy Renewable (PER) Demand (≤ 60 kWh/m².a*)	68 kWh/m².a

*+/-15 kWh/m².a allowance if offset by energy generation. See Passivhaus criteria.

Monitoring

The home’s performance is being closely monitored by the University of Strathclyde in collaboration with Kirsty Maguire Architect Ltd. Since late 2023, data has been collected on temperature stability, indoor air quality, humidity, and energy use.

Initial results indicate stable indoor temperatures throughout the year, excellent indoor air quality, and minimal energy consumption. This ongoing research will inform future Passivhaus projects and refine design strategies for even greater efficiency.

A real test came last winter when the temperature was below zero for more than a week. I was out of the country and everything was switched off at the house. Even with no heating it only lost one degree every 24 hours”

Kirsty’s home office sits in front of the house. Built to the same Passivhaus standard, it contains a workspace for Kirsty and a colleague, and a meeting room to discuss projects with clients.

If I can have clients in on a cold winter’s evening and it’s cosy and warm in here without any heating on, that shows them the comfort levels that a Passivhaus can bring”

Kirsty Maguire, Client & Architect, Kirsty Maguire Architect Ltd

The Silver House - Passivhaus Classic - Image © Kim Cessford

Services

A mechanical ventilation heat recovery system (MVHR) ensures a constant supply of fresh air while recovering heat from outgoing air, not only improving air quality but also minimisng heat loss and maintaining consistent humidity. A small air-source heat pump provides hot water. The house requires no central heating, with passive solar gain and insulation maintaining warmth. Infrared panels offer occasional heat boosts if needed. Wiring is in place for future solar panels and battery storage, allowing further reductions in energy costs. The house also includes an insulated, airtight cat tunnel, demonstrating that even pet access can be considered in Passivhaus design!

Challenges & lessons learned

Constraints: The north-facing slope, despite its constraints, contributed to an efficient heat load strategy, allowing winter sun to warm the home while preventing overheating in summer.
Measured performance: The house performed better than expected, with impressive energy efficiency and comfort.
Off-site manufacturing (OSM): Due to the site’s constraints, prefabricated Passivhaus kits couldn’t be used, though they would be beneficial for future projects.
Construction protection: Given the challenging terrain and site conditions, extra precautions were used to protect materials during construction.
Embodied carbon in retaining walls: While necessary for structural stability, the concrete retaining walls had a higher embodied carbon footprint.

The project also highlighted that many challenges in construction arise not from Passivhaus requirements but from external factors like site limitations and supply chain disruptions, such as insulation delays due to COVID border closures. However, tackling these obstacles with flexibility and resilience is key to successful project execution.

Silver House Passivhaus, Kirsty Maguire quote: People often think Passivhaus windows must be small or south-facing. I have a large north facing triple glazed window that minimizes head loss and improves comfort. Another misapprehension is that windows must stay shut, that's not the case, you can open them whenever you want

Key team

Architect & Passivhaus Designer: Kirsty Maguire Architect Ltd
Structural engineer: Burnett Consulting Engineers
M&E consultant: Luths Services
MVHR Designer: Paul Heat Recovery
Passivhaus Certifier: PHT Patron WARM

This Fife Passivhaus is a testament to how constraints can drive innovative, sustainable design. Despite its challenging site, the home achieves exceptional comfort, energy efficiency, and environmental responsibility. With continued monitoring, the insights gained will contribute to even more refined Passivhaus solutions in the future. Dive into more details about this project with Kirsty Maguire at the How to build a Passivhaus webinar series 2025.