As cities increasingly look to meet new climate goals, reducing building carbon emissions has become a primary focus. For good reason, around 40 percent of the country’s emissions come from buildings. High-rise apartments heated with central boilers are a particular problem as they are a major source of pollution. Converting these buildings from fossil fuels to electrification will go a long way towards increasing their energy efficiency.
This is what became apparent to the team at University Square, a 442-unit multifamily building in Philadelphia. My company Sentient Buildings recently installed a new system to better control heating and cooling of the property. We installed electric heat pumps and individually controlled thermostats in each apartment, and fully integrated this system to an existing gas fired central plant hot water heating system. By combining both systems, the building is now able to operate in a much more efficient way at higher and lower outdoor air temperatures.
Utilizing a cloud-based management platform, we also enabled University Square to centrally monitor all of the systems that exist in the building through a single platform. With the entire infrastructure streamlined into one location, users are better able to see what they want, when they want to. The solution put in place at University Square incorporates a unique heating system. It allows for local set point control by tenants, while also providing direct feedback to the central plant to run the overall boilers only when needed and at much lower temperatures.
Each unit has its own controls for heating and cooling, but they are only designed to generate heat when it is above 35 degrees Fahrenheit outside. This saves the central system energy by not having to automatically turn on to generate heat for the entire building. The central plant is still able to control a set point (a designated temperature limit) for the individual units, ensuring a comfortable temperature for all building residents, while also monitoring that no rooms are overheating.
Individual valve controls were also added to each apartment so that when temperatures fall below 35 degrees, the units can continue to be controlled to a set point. If it is warm enough in individual apartments, the valve can remain closed, which reduces the total amount of hot water required to be generated for the entire property.
University Square is a case study for the efficiency of separating heating into two stages, and could become a standard method in the future, as buildings start to convert their heating systems off of carbon based fuels to renewable electric based sources. Annually, the amount of savings building owners will be able to realize once a typical management system is installed is 20 to 30 percent, and possibly even more, while allowing occupants to have direct control over their own comfort.
While the in-room thermostats at University Square allow for more individual comfort, the system also limits the maximum set point that can be established, so that overheating and energy waste does not occur. This system will also be able to detect apartments that are exceeding the maximum set point established, or are unable to achieve a desired set point, and can alert management. This is problematic when the building is master metered, and management is trying to maintain an efficient system.
For example, with the central system there is the ability to monitor how long it takes an individual unit to reach the temperature threshold. If it goes over the set point, it is likely that the tenant is using an external heating source, such as an electric space heater. On the flip side, if the system has been running for several hours and has yet to hit the target temperature, this could indicate there is some sort of air infiltration in the room, such as a leaky or open window.
The system can make adjustments in real time, as well as flag declining energy efficiency and recommend solutions such as installing a new filter to clean dirty coils. Real time monitoring can also detect if there is something wrong in an individual apartment or heat pump.
The electric heat pumps installed at University Square operate as the building’s primary energy source above 35 degrees Fahrenheit, and provide more efficient, targeted heating and cooling to individual units when necessary. For example, some apartments may be naturally warmer during certain times of the day if exposed to direct sunlight.
Energy waste remains a significant problem in multifamily buildings. A common source of this waste is from air conditioning sleeves. In the instance of University Square, we took advantage of this setup and put heat pumps in all the sleeves. However, if the sleeve isn’t properly sealed to prevent air infiltration, or a unit in that sleeve doesn’t fit properly (which we see everywhere), there will be major problems with air infiltration getting into the apartment resulting in a huge energy loss. The solution is very simple: seal your open sleeves.
Many owners and landlords also allow their residents to supply their own air conditioner, and there is no guarantee that the tenant will install the right size unit. An improperly sized unit will more than likely cause air infiltration issues inside the apartment. The best thing for owners and operators to do is standardize how they control their heating and cooling system in each apartment, rather than leave it up to the tenants.
New technologies are continuing to enable greater energy savings in buildings. For example, heat pumps are becoming much more efficient, and enable using heat at a lower temperature and higher efficiency. This is a stepping stone in moving toward electrification of heating for gas, and moving away from carbon based fuel systems. The argument is that electric is going to be the way to provide heat in the future, because it will be possible to provide electricity through renewable sources including solar, wind and hydroelectric.
Sentient is also utilizing the technology employed at University Square in residential properties in Manhattan and elsewhere throughout the Greater New York area. With the Climate Mobilization Act recently signed into law by the New York City Council, approximately 50,000 existing commercial and residential buildings are set to be impacted. The bill package will require New York City buildings greater than 25,000 square feet to cut carbon emissions 40 percent by 2030 (from a 2005 baseline), and 80 percent by 2050. As legislators begin to focus more on the environmental impact of buildings’ carbon emissions, technology will be a key antidote to helping meet the new goals and standards put forth.
A number of programs are being run by Con Edison, NYSERDA and the Department of Energy to make it attractive for building owners in New York City to start implementing these changes now. In addition, buildings with affordable housing options, financial hardship or other unique conditions may be able to qualify for adjustments, exemptions or extensions.
While New York is currently taking the lead in requiring buildings to become more efficient, new legislation calling for greater energy efficiency will continue to go into effect throughout the United States, and buildings will need to become more automated to help meet these obligations.