Dillon House, USA: office building EnerPHit retrofit

ideadmin on 23 March 2026

Dillon House is a three‑storey, 5,800 ft² administrative building at Harvard Business School, home to the MBA Admissions office.

Dillon House, USA: historic office building EnerPHit retrofit

Passivhaus certification and Retrofit

Description

Dillon House, Harvard Business School — EnerPHit certification, design-stage review

Dillon House is a three‑storey, 5,800 ft² administrative building at Harvard Business School, home to the MBA Admissions office. Designed in Georgian‑Revival style as part of the original campus plan and ultimately constructed in 1965, the building’s cultural value and façade character were central constraints for the retrofit strategy.

RDH Building Science led the Passive House design consulting for the project. Praxis was appointed by designLAB architects as the Passivhaus Certifier.

Our Design Stage Review identified design strategies to meet EnerPHit+I Component Method certification. We also provided recommendations for alternative certification pathways, given that planning restrictions and cost constraints presented challenges for compliance with the EnerPHit Component and Primary Energy targets…for example, EnerPHit Step‑by‑Step: an approach that pre‑certifies the first retrofit phase against a comprehensive EnerPHit Retrofit Plan (ERP), with full certification upon completion of all planned steps (after achieving ≥ 20% reduction in PE/PER or demand in the first step).

Photo: School Wide

Year: 2024
Location: Harvard University, Boston, MA, USA
Architecture: DesignLAB Arquitects
Services provided by Praxis: Passivhaus certification and Retrofit
Classe de certificación Passivhaus: EnerPHit+i (Component method) Classic
Climate zone: Cool-temperate
Floor area: 331 m2
Thermal envelope area: 874 m2
Blower Door result: 1,04 n50
Heating Demand: 68 kWh/m2·a
Cooling Demand: 12 kWh/m2·a
Primary Energy Renewable consumption EPR: 170 kWh/m2·a
Final Energy consumption: 160 kWh/m2·a
Renewable energy generation: 0 kWh/m2·a
CO2eq emissions: 92 kg/m2·a

ICONIC: High performance sports centre, Andorra

praxisadmin on 10 January 2023

Cramea: centro deportivo de alto rendimiento

Description Passivhaus design and consultancy for a high-performance sports centre located at 2600 metres above sea level in El Pas de la Casa, Andorra. This 9000 m2 building, designed by Engitec, is in the process of Passivhaus Classic certification. Praxis has done the PHPP energy modelling, design of the thermal envelope and airtight layer, advice …

Cramea, High performance sports centre

Passivhaus

Description

Passivhaus design and consultancy for a high-performance sports centre located at 2600 metres above sea level in El Pas de la Casa, Andorra. This 9000 m2 building, designed by Engitec, is in the process of Passivhaus Classic certification.

Praxis has done the PHPP energy modelling, design of the thermal envelope and airtight layer, advice on low-impact materials, and analysis and optimisation of thermal bridges and construction details.

We’ve undertaken thermodynamic analysis of the building, using Design Builder (EnergyPlus), to assess thermal comfort and analyse the risk of summer overheating in critical zones in the building.

We have also consulted on mechanical and electrical system design, with proposals for improvements and compliance with the Passivhaus standard, to ensure efficient operation and low maintenance costs. Finally, we have provided with on-site Passivhaus supervision and quality control.

Year: 2022

Location: El Pas de la Casa, Andorra

Services Passivhaus design & consultancy, thermodynamic simulation, M & E consultancy, and site supervision

Deep energy retrofit, Pamplona: EnerPHit Plus

ideadmin on 30 September 2024

Rehabilitación de Vivienda en Pamplona: EnerPHit Plus

Description This deep energy retrofit of a semi-detached home is one of the first in Spain to obtain the EnerPHit Plus certification. The project was certified by Oliver Style of Praxis Resilient Buildings, with Passivhaus design by Alberto Jimenez Tiberio of Arrebol Eficiencia Energética. The dwelling, over three floors, belongs to a row of terraced …

Deep energy retrofit, Pamplona: EnerPHit Plus

Passivhaus Certification

Description

This deep energy retrofit of a semi-detached home is one of the first in Spain to obtain the EnerPHit Plus certification. The project was certified by Oliver Style of Praxis Resilient Buildings, with Passivhaus design by Alberto Jimenez Tiberio of Arrebol Eficiencia Energética.

The dwelling, over three floors, belongs to a row of terraced houses located in Beloso, Pamplona. The exposed brick facades and the aesthetics of the neighbourhood meant the house had to be insulated internally, mainly using mineral wool insulation. To meet the Passivhaus requirements, certified Cortizo A84 window frames were installed together with low emissivity, argon filled triple glazing.

The airtightness of the envelope was massively improved during the renovation, with an excellent result in the final blower door test of n50 = 0.64 ach.

Mechanical ventilation with heat recovery is with a Siber Excellent 4 unit, ensuring a high level of air quality. An air-to-water Mitsubishi heat pump was installed for heating and cooling (using underfloor heating and fan coils), and for domestic hot water production.

Solar photovoltaic panels were installed on the roof, bringing the house to EnerPHit Plus certification. The PV array generates, during a typical year, more energy than the house consumes.

Retrofitting an existing home to Passivhaus standard is a bold step in sustainability, reducing a building’s carbon footprint by reusing the existing structure and slashing operational carbon emissions. The project was certified to EnerPHit Plus by Praxis Resilient Buildings.

Links:

PEP (Plataforma Edificación Passivhaus)

iPHa (Base de datos internacional de proyectos Passivhaus)

Year: 2024

Location: Pamplona, Spain

Architecture: Juan Carlos Muguerza

Services provided by Praxis: Passivhaus Certification

Passivhaus Certification Class: EnerPHit Plus Certification

Climate zone: Warm Temperate

Floor area: 299 m2

Thermal envelope area: 730 m2

Blower Door Result: 0,6 n50

Heating Demand: 20 kWh/m2·a

Cooling Demand: 1 kWh/m2·a

Primary Energy Renewable consumption (EPR): 72 kWh/m2·a

Final Energy consumption: 43 kWh/m2·a

Renewable energy generation: 74 kWh/m2·a

CO2eq emissions: 23 kg/m2·a

Ajuntament Llinars del Vallès, Catalonia, EnerPHit Plus retrofit

ideadmin on 10 November 2025

Ajuntament Llinars del Vallès, EnerPHit Plus

Nestled in the Vallès Oriental region, the newly retrofitted Llinars del Vallès Town Council office stands as a pioneering achievement—the first administrative building in Catalonia to earn Passivhaus-EnerPHit certification

Ajuntament Llinars del Vallès, Catalonia, EnerPHit Plus retrofit

Passivhaus Certification

Description

A Milestone in Municipal Sustainability: Llinars del Vallès Town Council Office

Nestled in the Vallès Oriental region, the newly retrofitted Llinars del Vallès Town Council office stands as a pioneering achievement—the first administrative building in Catalonia to earn Passivhaus-EnerPHit certification. This landmark project sets a new benchmark for deep energy retrofits in public infrastructure.

The renovation delivers an impressive 90% reduction in heating and cooling demand, made possible by a robust envelope upgrade:

12 cm mineral-based aerated concrete ETICS on the façades
10 cm XPS insulation on the roof
Smartwin timber-aluminium windows, Passivhaus-certified, featuring low-e, argon-filled triple glazing

Airtightness was rigorously addressed, achieving n50 = 0.88 ach, well within Passivhaus standards.

Ventilation is provided by a Zehnder CARMA 9035 unit, also Passivhaus-certified, boasting an 84% heat recovery rate. For heating, the building taps into a biomass district heating network, distributing warmth via wall-mounted fan-coils—which also deliver summer cooling through a 30 kW chiller.

To further reduce operational carbon emissions, a 19.3 kWP solar PV array supplies approximately 70% of the building’s annual energy needs. Real-time monitoring systems track both energy consumption and indoor air quality, ensuring performance transparency and occupant comfort.

Photos: GGV Arquitectura

Links:

PEP (Spanish Passivhaus Platform).

iPHa (International Passivhaus Projects Database)

Year: 2024

Location: Llinars del Vallès, Province Barcelona, Catalonia

Architecture: Guarner Garreta Viola Arquitectura SLP – Lourdes Garreta & Xavier Tragant

Services by Praxis: Passivhaus Certification

Passivhaus Certification Class: EnerPHit Plus

Climate zone: Warm-temperate

Floor area: 768

Thermal envelope area: 1.428 m2

Blower Door result: 0,9 n50

Heating Demand: 18 kWh/m2·a

Cooling Demand: 4 kWh/m2·a

Primary Energy Renewable consumption (EPR): 43 kWh/m2·a

Final Energy consumption: 48 kWh/m2·a

Renewable energy generation: 33 kWh/m2·a

CO2eq emissions: 12 kg/m2·a