September 27th 2022

Submetering in IESVE and Operational Economics: Santa Fe Senior Village

Submetering in IESVE and Operational Economics: Santa Fe Senior Village

National Community Renaissance (National CORE) is a Developer/Builder of affordable housing, based in Southern California but with footprint reaching to other regions and States (currently Texas and Florida). In this guest blog, Tim Kohut, AIA, Director of Sustainable Design at National CORE, shares their approach to operational economics, using submetering within IESVE to identify how much and where their buildings use energy.

Ed Mazria and the team at Architecture 2030 were the first to point out that "Architects Pollute" (Metropolis, October, 2006) and soon after the American Institute of Architects recognized the responsibility resting on the shoulders of the profession to help solve the Climate Crisis. We are making progress, and many design teams routinely rise to the challenge. At the same time energy codes in many countries and U.S. States (like California) continue to evolve and push design teams towards higher energy efficiency and wider deployment of on-site renewables.   

There is a generational challenge to architects to unlock their inner engineering skills, identify the opportunities offered within the boundaries of energy codes, and to identify new styles and typologies that celebrate both sustainability and design. Even so, while the worsening impacts of Climate Change hit our news feeds each day, slow motion change and business as usual tendencies are the norm. A different approach and an alternative perspective - one that we all agree is important - is needed in conversations with our clients, one centered on economics and more specifically operational economics. What are the long-term economic consequences of design decisions? How do you measure? What do you share? How important is renewable energy? Who pays for what?   

All of these conversations are important for National Community Renaissance (National CORE). For us, first cost is important - our budgets are fixed - but equally important are the long-term operational costs for the buildings we're designing, developing, and building.  

For National CORE, the answer is simple. We build, test, and measure our assumptions in IESVE software. We use key features, especially the ability to create sub-meters so that we can isolate how much energy goes where, how much renewable energy we can accommodate on our buildings and, most critically, where the renewable energy gets allocated. We prioritize getting our common area electricity to zero first, then distribute excess energy to residential units, many times achieving Zero Net Energy.   

The following section outlines the National CORE approach to operational economics, which was recently applied to one of our current buildings, Santa Fe Senior Housing, located in San Diego, CA:

The Project: Santa Fe Senior Village
Location:  San Diego, CA
Type of Project: Housing for the formerly homeless
No. of Units:  54 (51 studios, 2 one-bedrooms, 1 two-bedroom manager's unit)
Energy Features: All-electric, max-fit PV system (possibly ZNE depending on budget)
Primary Funding Source: Low Income Housing Tax Credits
Schedule: Construction starting January, 2023.  Completion June, 2024

Energy Analysis, Defining Sub-meters and Operational Economics:  
In previous IESVE Case Studies (see the Iris at San Ysidro and Legacy Square), National CORE's approach to conceptual energy analysis and right-sizing HVAC analysis was discussed. The next step in our process is to identify how much and where the building will use energy. This data can then be used to identify how much it will cost to operate the building. We can also determine the impact of onsite renewables.

Working within IESVE, as the building envelope is optimized and the HVAC zones are created and HVAC sizing is completed, we focus on performance analytics in the VistaPro Application to determine energy use and operational costs. The workflow includes:

  1. For most projects, residents pay their own utility costs, so it's important for National CORE to identify common area energy use, so we can hit common area ZNE first. For us, ZNE is easily within grasp with large scale rooftop PV for buildings three stories or less. When buildings hit four stories or taller (as many of ours do), ZNE is harder to achieve (our four-story buildings offset approximately 60% of total energy with rooftop solar). Within Apache, we navigate to "Energy Sources and Meters” and define electrical sub-meters for specific building uses, isolating common areas (i.e. common area lighting, common area HVAC, elevators, washers and electric dryers, common area plug loads, ventilation fans) from residential uses (residential HVAC, lighting, plug loads, cooking loads). National CORE builds "all-electric" buildings, so we do not have other fuel sources. If you have other fuel sources (like natural gas), you can define submeters for these, too.

  2. Once the meters have been defined, we perform an annual simulation with APACHE. If you test different assumptions, be sure to give the APACHE simulation a unique descriptor, so that you can study the impact of each design strategy within the VistaPro Application. 
  3. IESVE users understand that the VistaPro Application provides advanced analysis & insight into building specific data (energy, heating and cooling loads, ventilation analysis, etc). Once the APACHE analysis is complete, proceed to the VistaPro Application and be sure to find your simulation file. Under "Categories", select "Energy" and select the "Energy Breakdown" tab. Expand the "Electricity" category to show the meters. Then identify the electricity loads you'd like to isolate and select the reporting method most appropriate to your analysis (table format, bar charts, line graphs). 

  4. IESVE has introduced robust utility tariff tools which help determine the costs to operate the building. Open up the "Tariff Tool" within the VistaPro Application and identify the utility company that will service your building. Utility schedules are tricky, so you will may need to consult with your electrical engineer, or your dry utility consultant to determine your probable utility rate. National CORE has a large existing portfolio of operating projects, so we can use similar buildings in the same utility service area to identify the probable utility schedule. Use the "Import Rates" button to open up a dialogue box to select your utility. Be sure to match the name of the utility as it shows on the "Utility List" button (which will hyperlink to a website with all U.S. utilities).

  5. Within the "Select" box, identify the appropriate utility rate. Santa Fe Senior Housing is a multi-family building, so it will use residential utility rates. Similar projects in San Diego Gas and Electric territory use the TOU-DR1 rate schedule, which we selected here, then "Import" is used.

  6. Next click on "Calculate". IESVE will use the actual rates for your building to identify the cost to operate your building. When the analysis is complete, select the middle tab "Annual Energy Costs" and identify the total cost to operate your building. For Santa Fe Senior Village, a-54 unit special needs project, we were able to anticipate the annual energy cost (based on current rate schedules) to operate our building. The VistaPro Application allows a fully-costed APACHE-Post-Processed (.APP) to be visualized, including the seasonal cumulative Time-Of-Use charges and the total hourly electricity costs. 

Final Thoughts & Conclusions:
Energy analytics, especially for affordable, multi-family housing, is a multi-step process, beginning with conceptual energy analysis, continuing into the HVAC system sizing analysis, then landing in analysis of costs to operate. For National CORE, cost analysis is the most critical step. It is our starting point for conversations with the design team: what can we do to get these operating costs down? How much PV can we land on the building and the site to minimize our long-term operating costs? From here, we can run other iterations to improve energy performance and we can optimize renewable energy deployment. 

In upcoming blogs, we'll explore the National CORE approach to optimizing onsite renewables for common areas first and residential units second, all the while exploring data analytics showing what operating costs will be.

The path to cost-contained, high performance affordable housing requires precision, and whenever possible, modeling efficiencies. NCORE relies on IESVE to help pin down critical analysis, providing detailed reports, paving the way for us towards zero net energy and carbon neutral projects. 

Continuing our exploration of how IESVE benefits the affordable housing projects we design, build and operate, Santa Fe Senior Housing is an example of how we can achieve a high-performance, climate-conscious and affordable building design within a limited budget, now showing how we can get into and fine tune operational economics to unlock long-term savings. The less it costs to operate, the more we can invest in high performance energy systems up-front.  

National Community Renaissance continues to lead the affordable housing industry, telling the real-world story, showing what is possible in affordable housing. When it comes to high performance, zero net energy, and carbon neutral projects: If we can do this, everyone can.

Tim Kohut, AIA, Director of Sustainable Design at National Community Renaissance, California