The Elk Ridge Passive House embodies the conscientious building practices of Passive House design through strategic planning, thoughtful design, and rigorous building standards. Similarly, the foundation of Glo European Windows was built on the desire to provide high quality, beautifully designed, environmentally conscious fenestration products that last a lifetime. The convergence of beauty and sustainability in the design of the Elk Ridge Passive House aligning with the values of Glo is no accident as the owner of this home is also the owner of Glo European Windows. Glo’s belief in preserving our world’s natural resources has been a key factor in pursuing Passive House both professionally and personally.
The hope in building a Passive House home is to further educate others on Passive House construction practices and change the way we build – with the ultimate goal of protecting our planet and leaving the world better than the way we found it. This four-part series is written with the intent of being a guide that others may use as they too embark on the increasingly important Passive House journey. We will walk you through the entire process of building a passive project from:
• Selecting the design team (architect, builder, consultants, subcontractors)
• Design process (preliminary planning to completion)
• Site selection (what to look for and how to overcome the obstacles)
• Material selection (lumber, air sealing materials, concrete walls)
• Window and door selection (types, performance, strategy, design)
• Mechanical systems (heating/cooling, domestic hot water, ventilation)
• Construction methods (roof design and insulation, soffits, wall assembly, air sealing methods, slab insulation, wall insulation and roof design)
• Finishes (cabinets, flooring, interior doors and trim, walls, bathrooms, kitchen)
Before diving too deeply into the overall process of Elk Ridge Passive House, let’s discuss some general principles and components that set Passive House construction apart from standard construction. Here are 5 basic design principles that every Passive home design strives to encompass.
1. Compact Building Shape
Reduction of the buildings’ exterior surface area allows for a home to more easily meet the stringent Passive House energy-efficient standard. The energy requirements are based off a ratio of surface area to building volume, also known as the “S/V ratio”. The surface area (S) of the building consists of walls, windows, ceilings, and roof. The volume of the building is the actual living space (V) within the home. The most efficient way to achieve Passive House standards, is to maintain a low surface area to volume ratio, with few projections, dormers or oriels. The lower the ratio, the less thermal energy it will require to comfortably heat/cool the home. More compact buildings tend to be more efficient to build as well.
(Please note the complexity/simplicity of the building shapes and the increase/decrease of the surface area and the implied complexity/simplicity of the energy requirements)
2. Continuous Insulation
The construction of the building should be insulated in such a manner that the building is able to maintain temperatures of 50 degrees or above without an active heating source. This is achieved in two ways; Thermal Bridge Free Construction and Air Tightness.
a. Thermal Bridge Free Construction – A “thermal bridge” is anything in the building envelope that acts as a “bridge” for thermal heat/cool to conduct from the interior of the building to the exterior. Many of these bridges are found in corner junctions, inconsistent insulation, concrete slab junctions at walls and balconies, openings/penetrations in wall assembly, metal studs or fasteners thru the entire wall assembly, to name a few examples.
(Elk Ridge Passive House Wall Assembly)
b. Air Tightness – A hazardous downside of thermal bridges is they can be a potential cause of condensation creating moisture, mold and rot within the wall assembly leading to building failure.
Thermal energy seeks the path of least resistance from warm to cold. Insulated concrete slabs, high-performance framing methods, elimination of metal fasteners, thoughtful junctions and continuous insulation creates a thermal bridge free and air-tight building envelope constructed for long term durability and performance.
3. Balanced Ventilation with Heat Recovery with Minimal Space Conditioning System
Since a Passive House building is airtight. An HVAC system should be selected that balances ventilation and moisture. This is achieved thru either an HRV (heat recovery ventilator) or an ERV (energy or enthalpy recovery ventilator). These systems supply fresh air to the building and remove stale air while recovering energy from the exhaust air in the process. The ERV transfers heat and moisture, while the HRV transfers heat. These systems are custom designed based off building specific calculations,cubic volume and building occupancy.
4. Optimal Solar Orientation and Shading
Optimal building orientation is important in order to properly distribute solar energy by collecting solar heat in the winter and protecting against solar heat in the summer. Proper building position in accordance to southern exposure is ideal to absorb and store solar heat. The prevention of overheating requires strategic shading for windows facing east and west. During the summer months overheating is prevented by thoughtfully sized overhangs, exterior shades, and the natural surroundings.
5. Energy Efficient Appliances and Lighting
Energy efficient appliances and lights produce less heat in their operation than inefficient ones. By choosing efficient appliances and lights, the house will stay cooler in the summer, and reduce the overall energy used in the building.
These 5 key standards will be evident throughout the Elk Ridge Passive House construction process. This series will dive further into each of these principles and how they were specifically executed for the Elk Ridge residence. Many challenges were overcome in order to adhere to the Passive House energy model, which was determined early on in the construction development.