The Orchards at Orenco achieves Passive House Certification
The Orchards at Orenco is the largest multi-family housing project in the nation to achieve Passive House certification.
Transportation, utilities and rent make up the largest part of an individual’s monthly budget. Aimed at reducing these costs, the project utilizes a variety of energy reduction strategies to provide substantial savings to residents. In addition to significant energy use and cost reduction, the building is also designed to provide tenants with comfortable and healthy homes. Located in Hillsboro, Oregon, Orchards provides 57 affordable apartments to serve the local workforce and is adjacent to the Orenco Station MAX (lightrail) to promote travel via public transit and reduce travel costs for residents.
Why Passive House
Passive House buildings are designed to be incredibly comfortable throughout all seasons, provide superb air quality and significantly reduce energy used by heating and cooling systems. The basic tenants of the Passive House design and construction strategies are a highly insulated and tightly sealed envelope and heat recovery ventilation. Achieving the performance-based Passive House certification requires meeting or exceeding stringent limits for heating (4.75 BTU/hr-sf) and total energy demand (38 kBTU/sf-year), and meeting a building leakage test of 0.6 air-changes per hour (ACH) at 50 pascals.
The efficiency, or tightness, of a Passive House certified building envelop also provides improved resiliency. When the building faces a power outage in a cold climate, indoor temperatures can be maintained for an extended period of time.
Creating a Comfortable, Efficient and Healthy Home
The building is served by three heat recovery ventilator units located in penthouses that supply air directly to each bedroom and exhaust air from the bathroom and kitchen areas. Ventilation air is heated or cooled utilizing a variable refrigerant flow (VRF) system to provide conditioned air to each apartment, resulting in excellent indoor air quality. This system provides a majority of the heat required to keep the units comfortable, but electric heat is also provided to give tenants further control of their space temperature.
The central domestic water system utilizes high efficiency condensing water heaters and a heat tape temperature maintenance system for hot water distribution. The heat tape temperature maintenance system utilizes less energy than a recirculating water system and helps save water by ensuring hot water is available at all fixtures without delay. To further reduce water use, low-flow water fixtures were installed.
The Orchards at Orenco building was completed in June 2015 and received Passive House certification in the same year. It achieved an incredible air tightness of 0.13 ACH at 50 pascals - among the tightest buildings in the world. The Orchards’ metering system confirms that the building is performing as modeled, and is achieving approximately 70% energy savings, when compared to a typical benchmark established for this type of project.