Energy Efficiency Solutions

Thursday, April 23, 2015

Purpose of the project:

The existing 500-gallon hot water storage tank and boiler systems at the subject senior housing community, Sunrise of Sunnyvale in Sunnyvale, CA, were at the end of their useful life. Instead of replacing the systems on a like-for-like basis, more cost effective and energy efficient solutions were desired and investigated. The antiquated tank and boiler systems were replaced with eight Rinnai tankless exterior hot water heaters, which resulted in significant energy and capital savings.


Across our Sunrise portfolio, we are collaborating with our operating partner to maximize environmental awareness and the sustainability of our properties. Sunrise of Sunnyvale was an excellent sustainability enhancement candidate. Not only was the existing equipment at the end of its useful life, limited space inside the mechanical room would’ve resulted in the community being without water for days if a traditional interior system was installed. Rinnai’s exterior tankless system is made of stainless steel, enabling it to withstand the weather, as well as guard against California’s hard water that corrodes typical black iron storage tanks.

When choosing the proper number of units to install, peak usage, redundancy in the event of unit failure, and energy savings optimization were all considered. Of the eight units at the community, two provide water temperatures hot enough for the kitchen and laundry areas, while the remaining six units provide hot water to the resident rooms. This configuration enabled the modulating units to sync up, taking turns working together and only when needed, so they’re inherently a more energy efficient system right from the start. When a unit is running, the high-powered heaters instantly establish the target water temperature as it flows through the tankless units. With the exception of a minimal amount of water in the heat exchanger coils, water is not retained in the system, thereby significantly reducing energy usage versus a tank and boiler system.


The cost to install a like-for-like boiler system was almost twice the cost of the tankless approach ($88,500 vs. $45,356). Additionally, the tankless system resulted in $10,446 in energy savings in the first year of operation, contributing to total savings of $53,590. Aside from the financial results, the community received its fourth consecutive ENERGY STAR certification and this project served as a successful pilot for the implementation of other tankless hot water systems within the portfolio in 2015.


“Sustainability is integral to our business. We constantly identify areas where capital investments will increase a property’s efficiency. These practices benefit everybody -- society, our tenants, our residents and our investors -- and that is why we have made leadership in sustainability a key corporate value.” - Doug Johnson Vice President, Construction and Development