Weinberg Commons, DC

Insights –
Would Do/Not Do Again

As one of the first PHIUS+ multifamily retrofit projects in the country, Weinberg Commons taught the project team important lessons from the design phase through the post-build. Most importantly, this project revealed the importance of buy-in from all parties on the mission, goals, and budget of the project. Because of the intricacies of passive building design, this consensus is even more critical in terms of the pre-construction relationship with subcontractors. More time spent educating subcontractors on the project would mitigate learning curves and reduce the inaccurate pricing and multiple change orders that occur when subcontractors lack basic knowledge and context of the project.

Specifically, the team learned the importance of hiring experienced air sealing and insulation subcontractors and including concise passive building air sealing and sequencing requirements in all contracts to be agreed upon by all parties. As a pioneer project, these lessons are inevitable and illuminating. Assembling a qualified and fully dedicated team who has delivered other passive building projects of the same scale and difficulty level is critical to completing the next such project on time and on budget.

Insights – Great Ideas

Ventilation tied back into the ERV is typically a big discussion for passive multifamily projects. Individualizing ERVs per dwelling unit can become costly, provides excessive equipment for the combined occupant load, and has a greater chance that resident control will override its effectiveness. The team's solution was to split 12 dwelling units per vertical tier, therefore serving three dwelling units with one ERV, one vertical shaft, and very minimal distribution duct length within the actual apartment units. This strategy was successful because of its simplicity, enabling the team to control and limit disturbance to the building’s existing interior walls and ceiling finishes and use bulkheads only minimally. Because of the size (apartment unit air volume) and relative lack of height, stack effect was not as large a concern as in larger buildings. The implemented solution cut the potential equipment cost by approximately half and optimized the livable area of what were already very small two-bedroom apartments.

The poor orientation of the existing buildings for passive gains drove the design of fixed shading. Two faces are due east and west while one is 45 degrees from the cardinal points, exposing the main facades of the buildings to undesirable summer and shoulder season morning and afternoon sun, and limiting the use of available solar radiation during the winter. To respond to these conditions, solar altitude and azimuth were drawn and fixed and tapered external shading boxes were designed to mitigate cooling season gain and preserve heating season gains to the greatest extent possible. The tapered boxes also preserved light apertures for daylighting. Across the three buildings on the site, five unique geometric aperture profiles were designed and distributed among the 12 primary facades. The boxes were stick-built and framed in with the outrigged wood I-joist assembly, essentially eliminating thermal bridging back to the structure of the original building. During the design phase there was a question of how to make these boxes customizable to the variable building orientations and window size locations, while also durable, cost-effective and complementary to the overall building’s aesthetic. Extensive solar analysis and constructability details were critical to the process. Ultimately, the interior spaces are very comfortable. Solar exposure on an hourly basis optimizes passive gain to more than adequately meet the PHIUS+ annual energy budget for heating and cooling while maintaining open views to the exterior. The assemblies have created a unique visual character to Weinberg Commons, where its function very literally informs its form.

Insights – Benefits to Owner/Selling Passive Buildings

Our primary benefit is the health and comfort of the residents of Weinberg Commons. Housing Up is a nonprofit developer and service provider, and our key focus is always the well-being of the more than 600 families we serve. The passive building envelope and continuous low-flow filtered ventilation systems provide the highest quality interior environment and indoor air to the families living at Weinberg Commons, in a city where most of the affordable housing stock is severely outdated. The decreased operating costs provided by energy savings make Weinberg Commons an affordable project for us as the building owner, and more importantly, lower actual living expenses for the residents. Housing Up realizes that to continue to make truly affordable housing, reduction of residents’ costs and the improvements to their living conditions are essential to our mission.

The original buildings that comprise the Weinberg Commons project are representative of a significant proportion of the housing stock in the neighborhoods of Washington, DC where affordable housing is most desperately needed. This housing stock is, for the most part, very poorly performing, outdated, and unhealthy. The team believes that this project and others that follow will prove to be cost-effective, particularly as techniques are refined and contractors are educated. A simple cost-benefit analysis of Weinberg Commons simply cannot capture the reality: these buildings must be retrofitted aggressively to achieve decreased carbon emissions and climate change mitigation goals in our urban environments and improve the lives of our residents.

Mold and indoor air quality problems are quite common in typical retrofits of older buildings because of a variety of issues that passive building practitioners are well aware of, such as: part load condition humidity, inappropriately placed vapor barriers, duct condensation, high cost of occupancy, and airborne moisture infiltration. It is rare to hear a developer or builder acknowledge how many of these external liabilities have been reduced and how much those reductions might impact costs typically associated with passive building upgrades. These externalities represent a serious cost to the occupants, the District, and the world outside of the nation’s capital.

Pursuing Weinberg Commons may have appeared to be an unwise application of passive building principles to some, and may even stretch the simple energy reduction cost benefit premise, but projects like these must be completed on a broad scale to avoid the decimation of our existing urban fabric. To the team, undertaking the Weinberg Commons project was a financial, environmental, and moral imperative.