Reaching for Zero Energy in High Density Housing

Nearly 40% of the greenhouse gases released by buildings are caused by them. Therefore, there is a push to get to zero on all fronts. What happens when ambitious goals such as zero energy are met by a traditional building industry that is based on repeatability and cost in a market that can’t keep up with huge demand? This is often– way too often-–our challenge.

Housing is a very special type of building. Housing is a special type of building. It determines how people live and provides access to vital services. In fact, it can even predict the health, wellbeing, and resilience for entire communities. Housing is an essential part of the solution for climate change. However, carbon emissions directly linked to buildings’ design are only one part of this picture. It’s difficult for sustainable design standards to define what “good” looks for any particular housing project. The right priorities are complex and specific to each site.

Housing faces a dilemma when trying to reach zero energy. It sends a clear message about what we want: housing that is independent and part of the solution. But, if zero-energy goals dominate the conversation, it can limit a design team’s ability to identify strategies that could be equally or more effective for a community, and that come at minimal or no cost.

© Bruce Damonte

Zero-energy buildings are most often understood to be highly efficient buildings that produce as much energy annually as they use. This is usually done using on-site solar panels. This housing concept presents the greatest challenge in terms of density. Denser construction is the key to reducing transit emissions and displacement. This goal can be achieved by having fewer stories and smaller units. Although taller buildings consume more energy than those with solar panels, the effect of height on energy use intensitydown is beneficial at a regional level. Energy use intensity (or EUI) is the amount of energy consumed per square foot over the course of a year. Denser buildings tend to increase EUI, making it more difficult to reach a zero-energy target. This is because, even though they offer more homes in the same space, there are also more televisions and refrigerators per square foot in smaller units. To reach zero, you would need to invest in more complex renewable technologies and off-site sources of renewable energy. This may not be the best use of resources.

Building taller and denser buildings is more expensive per-building. Many buildings are likely to be a net positive for the climate if they are used as primary residences, are safe and healthy, and keep people in their communities. While this does not negate the ethical obligation of architects, it does highlight the importance of considering the context of land use and planning.

We want to be focused on an efficiency goal when it comes to energy targets in the work we do. This is the “lowest achievable” gross EUI for dense urban multifamily buildings. This is a rough definition of what current technology can achieve. It is based on the most recent industry benchmark modeling for multifamily buildings in mid-rise.

David Baker Architects is the firm that I work for. They have two projects completed that meet these “lowest attainable energy benchmarks: Coliseum Place, and Edwina Benner Plaza. Both are all-electric and have significant solar production. Coliseum Place is a six-story affordable housing project with 59 units. The EUI was just released in Oakland, California. Its predicted EUI is now 17 kbtu/sf/year. However, it drops to 9 kbtu/sf/year when there’s on-site solar PV. This may sound admirable but we will not stop applauding. It is not unusual for buildings that are completed to consume 20% to 50% more energy than expected. This can be due to poor initial modeling and the use of natural gas for hot-water heating. This significant discrepancy is also due to a dearth of testing, verification, or commissioning in multifamily housing.

Edwina Benner Plaza is our first all-electric building. It has been occupied for three year and is almost operating as expected at 16.7 kbtu/sf/year, before accounting for PV. This is due to the special attention given to monitoring the building’s energy consumption and making sure that its super-efficient heat-pump hot-water system works optimally. This project does not include any other emerging technologies. For multifamily housing it is still the small innovations that can offer the greatest potential to reduce emissions. This demonstrates why “zero” may not just be about new technologies or renewable energy solutions. It could also be about driving change in process. A closer look at the purpose and goals for climate-responsive housing is needed.

via David Baker Architects

FIVE WAYS THAT WE CAN THINK DIFFERENTLY

1. Set clear goals.

Setting clear and achievable goals is the first step to climate-responsive multifamily housing. It’s important to make sure they are right, that they are realistic, and that you have a strong commitment. This goal should answer the question: What wouldit look to allow this project to “stand alone” and contribute to the climate solution? The goal should include an EUI target and as much PV as possible. Energy accountability is definitely part of the solution. However, the goals should be natural and appropriate to the strengths and weaknesses of a particular community.

2. Evaluate the value and cost.

Next, the team will use design tools to help them evaluate design options based on value. This is a measure of the ability to achieve the project’s goals and not cost or compliance. Without a clear purpose beyond “four walls and roof”, cost and compliance are the most important decision-making factors. We use comfort models and resilience-planning rubrics to track the predicted outcomes of our decisions.

3. Connect value to social equity

The team should consider the improved opportunities for residents and the complex relationship between technological innovation and social equity when defining “value”.

Coliseum Place taught me that energy efficiency was the most important selection criteria for residential heating, cooling and ventilation systems. There are few HVAC options available and they can have huge cost implications. Residents must prioritize their health, comfort and dignity. Good news is that efficiency doesn’t necessarily have to be sacrificed for human benefit. The attitude and approach are important. If we are to recognize the many ways that the design of our neighborhoods and homes affects our quality of living, this logic should be applied to all areas. It will be more difficult to reduce housing’s overall footprint if residents are forced to live in unsafe, isolated, or unhealthy homes.

Multifamily housing emissions can be reduced by ensuring equal access for all income levels to technology that allows them to thrive in a changing environment. This imbalance in access has been brought to a climax by the pandemic. This also highlights a relatively inexpensive measure that may seem outside of the scope for a zero-energy discussion, such high-speed internet or virtual mobility. This essential service is not available to many low-income households, which can limit the community’s ability for growth, whether it is pandemic or not. Although buildings can’t fix systemic inequalities, this is the kind of blind spot that we can have if global, greenhouse gas-reduction targets define how we think sustainable housing.

4. Remember carbon

Zero-energy buildings may have different carbon reduction profiles. They still use grid electricity and can contribute to a greener grid. Load shifting and storage strategies can help to reduce future emissions and save owners money. They also contribute to community resilience. These things can be done without going to “zero.”

Another important factor is embodied emissions. Coliseum Place showed us that while it is easy to reduce embodied carbon emissions in multi-family buildings, there are other factors. KPFF, our structural engineer, explained to us that we could reduce the emissions from the concrete foundation by using lower-carbon options and replacing as much cement as possible. This was the same amount of carbon dioxide reductions our zero-energy measures would achieve by 2030 based on a rough estimate.

5 – Commit to verification, training.

Our last and most significant change is not new but it is still a new phenomenon in this sector. It would involve a thorough but basic examination of envelope-framing efficiency and insulation installation, air tightness, hot water distribution efficiency, and system commissioning. This could include pre-programming thermostats or giving residents detailed information about their apartment’s systems. This work is relatively inexpensive in the context of large system decisions. Setting the tone can influence everything, from pre-construction meetings that are more productive to handoffs between residents and building operators to successful handoffs. Coliseum Place will achieve its EUI goals by ensuring that residents are comfortable with their systems and that the distributed hot water system functions as it should. This is possible because of thoughtful and deliberate communication with the building manager regarding the design.

There are many things we can do immediately and much more that we can strive for over the next few years. We must rethink the way we approach every project in order to reduce emissions and reverse global warming. Recognizing that climate-responsive design does not have to be about achieving a single, absolute goal like zero energy is part of this process. Housing providers have the power to combat climate change by ensuring and expanding local benefits (stability. health. adaptation). This requires us to have a better understanding of what “zero” energy and carbon means for housing.