ZERO. As in net zero or Zero Energy Ready Homes (ZERH).
The watchword for the industry. A path forward for our buildings.
This type of home, which outperforms today’s standard to-code buildings and delivers the opportunity for ultra-low or nonexistent energy bills, is also an exciting growth industry. While a relatively small percentage of home builders are constructing them today, their popularity only keeps rising. There are 18 local governments globally, including six in the U.S., with commitments to net-zero new buildings by 2030 and for all new and existing buildings by 2050.
But… is it realistic?
What Makes a Zero Energy Ready Home?
The U.S. Department of Energy wrote the spec on ZERH, and the program is finally taking off. Market surveys show building commitments and interest in zero has doubled from 2017-2019! The DOE has seen certifications doubling for the 3 past years. There is also increasing state code interest in zero, from California to Arizona to New England. But what exactly is a zero energy ready home
A zero energy home is not just a “green home” or a home with solar panels. Similar to Passive House, zero energy homes are ultra-comfortable, healthy, quiet, sustainable homes that are affordable to live in. They are regular grid-tied homes that are so air-tight, well insulated, and energy-efficient that they produce as much renewable energy as they consume over the course of a year, leaving the occupants without an energy bill and with a healthy, comfortable, carbon-free home.
There is, of course, a spec sheet. To be a Zero Energy Ready Certified building, homes need to:
- Include energy-efficient appliances and fixtures
- Have windows that meet ENERGY STAR v5.0 and v6.0 specifications (depending on climate zone).
- Comply with EnergyStar checklists for thermal enclosure, water management, HVAC quality installation, and target home size adjustment factor
- Have insulation that meets 2012 International Energy Conservation Code levels
- Follow provisions from the Consolidated Renewable Energy Ready Home checklist to ensure future cost savings on solar installations
- Follow Indoor airPlus specifications to achieve high indoor air quality
- Conserve water and energy by using systems that provide rapid hot water
- Ensure proper ventilation using ducts and systems such as ERVs or HRVs
The DOE Zero Energy Ready Home checklists provide links to technical guides for each measure included in the checklists for DOE’s Zero Energy Ready Home National Program Requirements. But that’s just the basics.
According to one key expert, ZERH is more than a checklist.
Sam Rashkin and The Future of Home Building
Providing American homeowners with better homes that live better for lower cost of ownership is the mission of ZERH. “In fact, hundreds of homes on the DOE Tour of Zero are demonstrating tens of thousands of dollars of utility bill savings and often over $100,000 of savings over a 30-year mortgage while providing homes that deliver superior comfort, health, durability, and future value,” says Sam Rashkin, Chief Architect of the Building Technologies Office in the Office of Energy Efficiency and Renewable Energy, DOE.
So… How realistic is this? How will it affect builders? Why should they care? And, will builders comply?
For the DOE, the emphasis on providing a transformation to Zero Energy Ready Homes by 2030 means delivering hundreds of billions in energy savings back into the economy, creating millions of job-years of work that cannot be outsourced, and reducing emissions on the scale of millions of tons, making cleaner air for all Americans.
“The biggest thing I like people to understand is that, as we reach the seventh year of the ZERH program, you’re seeing a heavily vetted technical spec, which is fine-tuned on a regular basis,” says Rashkin. Builder partners who are engaged in ZERH are getting amazing outcomes. A look at the success of residential construction firms like Mandalay, Thrive, and Insight shows zero energy does align with business interest.
Rashkin advises looking beyond first costs. While certain measures and methods may require more expenses in some areas, they translate into savings in others. “It’s all about weighing credits and debits,” Rashkin says. For larger homes, the more efficient, airtight envelope means eliminating the multiple mechanical systems that are usually necessary to maintain comfort. Using a sealed, unvented attic for mechanicals means eliminating the expense of creating a basement to house HVAC and hot water. Leading ZERH builders advise that, while their product might cost a homebuyer 5 to 10% more to purchase than a to-code home, the homeowner will more than recoup that expense, realizing utility savings from $100,000 to $200,000 over the 30-year mortgage.
Consumers are generating their own demand for ZERH, becoming more informed thanks, in part, to technology. Smartphones and apps are changing the way consumers shop, buy and/or build a home.
Take WiFi thermostats, like Nest, for example. More than simply adjusting the temperature in your house when you turn the dial or press the buttons, WiFi thermostats allow you to monitor your energy usage, easily program daily schedules to save you money, and some can be part of an integrated smart home system working in tandem with security systems, automated lighting and more.
How about infrared, thermal cameras? Ten years ago, only home inspectors had access to these expensive tools. In the very near future, smartphone apps will allow Realtors and buyers to physically see thermal defects, water damage and moisture problems with the snap of a photo.
According to Rashkin, that’s only the tip of the iceberg. More educated consumers demand more tactical information. Buyers will demand HVAC quality and Indoor Air Quality scores. Utility bills for any given home or area will be searchable online. And HERS scores will become part of the MLS structure, much the way energy efficiency is used to market homes in Europe.
Tip, Techniques and Resources for Builders and Contractors
Technically speaking, builders are employing the following techniques to reach Zero Energy Ready:
- Zero Energy Ready Homes generally have walls that are framed wider and studs that alternate in a zigzag pattern to avoid “thermal bridging”, a situation where energy easily escapes.
- Constructing “California corners” allows for more insulation to be placed in corners of rooms, eliminating cold dead spots and energy leakage.
- Windows and doors are of the highest quality.
- Homes are extremely airtight, but have state-of-the-art ventilation systems that control air quality, heat and cooling.
- Pre-cast foundations are exact and strong, and slabs are completely detached from the earth.
- To maximize energy efficiency and improve home performance, these homes used unique construction methods such as structurally insulated panels (SIPs) wall and roof systems, exterior fluid-applied air barriers, and insulated concrete forms (ICFs).
- Grid-tied solar photovoltaic (PV) panels currently provide the most cost-effective form of renewable energy for a zero energy home. They can power all the energy needs of a home including lighting, heating and cooling systems, appliances and hot water. However, they are the most expensive component of a zero energy home and strategies for reducing or mitigating those costs are important to consider.
Many legitimate green builders practice similar ideas today, but it’s the “ready” in Zero Energy Ready that really takes this program into the future.
“We’re really proud of the Building America Solution Center as an amazing free tool for the industry, to help builders get to any high performance spec or achieve ZERH,” Rashkin says. “This is not fixed content, but free access to world class research that’s constantly monitored and updated.” Articles cover both new and retrofit practices.
Still not sure what that looks like? Take a virtual tour of the award-winning homes independently certified to meet DOE Zero Energy Ready Home.