Create an Energy Efficient, Fresh Air Supply and Manage

9. Create an Energy Efficient, Fresh Air Supply and Manage

  • Install a highly efficient Energy Recovery Ventilation (ERV) or Heat Recovery Ventilation (HRV) system to provide fresh filtered air. Learn more about HRVs and ERVs from Green Building Advisor
  • Depending on energy modeling results, consider selecting the more energy efficient HRV or ERV systems, such as the UltimateAir RecoupAerator 200DX ERV, the Venmar EKO 1.5 HRV or the Zehnder ComfoAir, or consider less efficient, lower cost units such as Life Breath ERVs and HRVs or Panasonic WhisperComfort ERV. View the Heat Recovery Ventilation video.
  • Plan for and manage moisture. In most homes, but especially airtight homes, indoor winter humidity should be 30% or a little below, to avoid possible condensation problems. While utilizing either a HRV or an ERV will help manage interior humidity, an HRV may help lower indoor humidity more effectively, when the outside humidity is low. The use of vapor barrier paint on the interior of the sheet rock will help prevent moisture from penetrating the wall assembly. And just moving the air regularly with either type of ventilation system will help prevent mold.

Twelve Steps to Affordable Zero Energy Home Construction

Use the Sun for Electricity and Hot Water

8. Use the Sun for Electricity and Hot Water

  • Based on energy modeling, determine an optimally sized Solar Photovoltaic (PV) System sufficient to meet the energy needs of the house after all other energy-saving measures have been taken into consideration. View the Solar PV video.
  • Get several quotes from reliable installers to get the most cost-effective system. Consider a leasing program, such as Sun Run, which can eliminate up-front costs; or consider financing your solar system through your local credit union.
  • Consider designing and building the home to be a “net zero ready” or “net zero capable”– a highly energy efficient home, sized and wired for future solar PV installation, which could become a zero energy home when the solar photovoltaic panels are installed.
  • Consider using solar PV panels to heat water instead of a solar thermal water heating system. As solar PV is becoming less expensive, it may be more cost-effective to add a few more solar PV panels to power an inexpensive, well-insulated standard water heater, instead of adding a solar hot water system. This can simplify zero energy home maintenance for the homeowner, and lowers costs for builders.
  • In warmer climates consider the cost-effectiveness of using a heat pump hot water heater, such as the G.E. GeoSpring Hybrid Watet Heater, the A.O. Smith Voltex Hybrid Electric, or the AirGenerate AirTap Hybrid in conjunction with solar PV. The AirTap can be vented so that the cold air exhausted from the system can be sent outside.

Twelve Steps to Affordable Zero Energy Home Construction

Use the Sun for Passive Solar Gain

7. Use the Sun for Passive Solar Gain

  • Use Solar Tempering, which uses the principles of Passive Solar without the added cost of adding thermal mass to partially heat the house. View the Solar Tempering video.
  • Use higher Solar Heat Gain Co-efficient (SHGC) windows on the south side with a SHGC of about 0.4 or more, if cost-effective.
  • Have approximately 50% of the window area on the south side, or have the south side windows equal 6% of the window-to-floor-area (WFA).
    Use optimal roof overhangs for maximizing winter sun and ensuring summer shade to the south windows.
  • Calculate the BTU gain from passive solar or from solar tempering during the design phase.
  • Consider installing insulated honey-comb shades, such as the Duet Architella shades from Hunter-Douglas, which may have an R-value of close to 4, in order to help keep out cold or heat depending on the season. They should be installed with minimal gaps at the edges or in tracks to be most effective; and the homeowner must be willing to close them on cold winter nights and on hot summer days.

Twelve Steps to Affordable Zero Energy Home Construction

Use Highly Insulated Windows and Doors

6. Use Highly Insulated Windows and Doors

  • Use insulated fiberglass doors with tight air seals.
    Aim for a 14% window-to-floor area (WFA) for the whole house, with about 50% of the windows on the south side, where the common living areas should be located. Depending on local circumstances however, more windows on the south side may not always be cost effective. These are all things that should be decided in the design phase.
  • Use triple-pane windows with approximately 0.2 U-value, such as Harvey Tribute, Thermotech, Atrium Northwest, Cascade, Solar View, Intus, Milgard or Alpen. Some double pane windows such as Milguard’s I-89 StyleLine, are achieving u-values close to 0.20 and should be considered.
    Fixed windows and casement windows with multi-point locking hardware are more energy efficient than sliders and single or double hung windows, both of which have leakage issues.
  • Look for windows that have the smallest frame profile because the frame has a higher thermal transmission than triple pane glazing. It is more energy efficient to use fewer larger windows with the same glazing area as more numerous smaller windows, because larger windows have a higher glass to frame ratio.
  • Depending on energy modeling, current pricing and advances in technology, shop for the most cost-effective, energy efficient windows. Less expensive triple pane windows may be the most cost-effective in many applications. In some climates and applications, energy efficient double pain windows may be sufficient.

Twelve Steps to Affordable Zero Energy Home Construction

Minimize Thermal Bridging

5. Minimize Thermal Bridging

  • Thermal Bridging can best be minimized in the design phase by a designer who includes cost-effective thermal-bridge-free details. View the Thermal Bridging video.
  • Use a Thermal Enclosure Checklist or Thermal Enclosure Checklist Guidebook to help you design and build with minimal thermal bridging.
  • Where thermal bridging cannot be avoided, closed cell spray foam or aerogels may help reduce it, but may not be cost-effective, compared to eliminating thermal bridging in the design phase.
  • Decks, porches and porch roofs should be designed and constructed to be separate from the house, so no thermal bridging occurs between the house and the porch or deck.

Twelve Steps to Affordable Zero Energy Home Construction

Super-Insulate the Building Envelope

4. Super-Insulate the Building Envelope

  • Use advanced framing techniques to save wood and allow space for insulation.
  • Use double 2×4″ walls, with off-set studs on 24″ centers, spaced 5″ apart, to form a foot thick wall cavity in northern climates. In more moderate climates, double walls with an 8″ or 9″ cavity may suffice, depending on the R-value that needs to be met. View the Double Wall Construction and Blown –in Insulation video.
  • Use raised-heel trusses to provide ample space for ceiling insulation. View the Raised-Heel Truss video.
  • In colder, northern climates, fill walls and floor with dense-pack fiberglass or cellulose to get to R-50, and blow in loose-pack ceiling insulation to R-60. Lower R-values may suffice in warmer climates.
  • Always ask for bids for R-value rather than thickness of insulation.
  • Utilize energy modeling to adjust the above R-values higher or lower for local climate and weather conditions.

Twelve Steps to Affordable Zero Energy Home Construction

Super-Seal the Building Envelope

3. Super-Seal the Building Envelope

  • Set an airtightness standard of 0.6 to 1.5 ACH at 50Pascals and create an airtight barrier around all six sides of the home. Depending on climate, a 2.0 ACH may be sufficient.
  • Use a Thermal By-Pass Checklist short form to identify areas that need sealing. The Green Building Advisor has excellent air sealing diagrams, available for free if you sign up for their 10-day free trial.
  • Ensure that exterior sheathing materials should does not have any gaps, and joints are mechanically tightened.
  • Seal the outer sheathing and the drywall ceiling before the inside drywall is installed. To learn more about exterior air sealing, see Airtight Wall and Roof Sheathing: Arguments in Favor of Exterior Air Sealing, and view the Exterior Air-Sealing video.
  • Use glue, caulking, spray foam, and/or products, such as Ecoseal or Siga Airsealing Tapes, depending on the size and location of the leaks. For more on sealing air leaks see Tape It? Seal It? Glue It? Sealing Weather Barrier Seams.
  • During the sealing process, check for air leaks with your hands and/or with a smoke stick while the blower door is running. Then seal the leaks and recheck. This is called Blower-Door-Directed Air Sealing. View the Blower Door Directed Air Sealing video.
  • Complete the air sealing along with the subcontractor and crew – be fanatical, systematic and persistent in finding and sealing every leak, checking your success with the blower door as you go.
  • After the sheet rock has been installed on the walls, seal the inner envelope while again checking with the blower door in order to identify and seal all remaining leaks while the blower door is running. View the Sealing the Interior Walls video.
  • Seal electrical boxes and plumbing penetrations after all electrical and plumbing work is complete. Consider using airtight electrical boxes on all exterior walls.
  • Minimize penetrations of the airtight envelop by:
    >>> Having all Ducts Inside and using track lighting, pendants, or recessed cans in soffits to keep the air barrier intact instead of using typical recessed can lighting. View the Ducts and Cans Inside video.
    >>> Using the Energy Efficient Whole House Ventilation System, either an ERV or HRV, instead of standard bathroom or kitchen vent fans, provided the ERV or HRV vents are sized properly for venting the bathrooms and/or kitchen, and that this is allowed by local code, which it often is.

Twelve Steps to Affordable Zero Energy Home Construction

Use Energy Modeling for the Most Cost-Effective Zero Energy Home

2. Use Energy Modeling for the Most Cost-Effective Zero Energy Home

  • The design should then be run through energy modeling software to ensure that the zero energy goal can be achieved with this design in a highly cost-effective manner. Based on the results of the energy modeling, the design may need to be modified to reach the net zero energy goal.
  • It is most effective to conduct energy modeling on different sets of energy-saving features during the design phase in order to determine the most cost effective mix of energy saving features that you are considering and to determine the smallest solar PV system necessary to achieve net zero energy for your design.

Twelve Steps to Affordable Zero Energy Home Construction

Design for Zero Net

1. Design for Zero Net

  • Cost-effective zero net energy homes begin with the design. This is a very critical starting point!
  • The designer or architect should be familiar with all the steps involved in building a net zero home as outlined below, and should design the home so that these steps can be achieved in as cost-effective manner as possible.
  • The design should specify the following: the siting of the home to take advantage of the sun; the wall, floor and ceiling systems using advanced framing techniques; the insulation R-values for walls, ceiling, and floors; the airtightness standard for the building shell; measures to avoid thermal bridging; the window type, locations and u-values; the door type, locations and R-values; the hot water system and its efficiency rating; the ventilation and heating/cooling systems and their efficiency ratings; the southern roof over-hangs to maximize winter sun exposure and minimize heat from the summer sun; the appliances and their efficiency ratings; the roof size, pitch and orientation to get the most benefit from the solar panels installed; and all other measures that are needed for the home to become a net zero energy home in the most cost effective manner.

Twelve Steps to Affordable Zero Energy Home Construction

Managing Yourself: Keeping Your Colleagues Honest

Jonathan has a new job. Just promoted from the accounting group at headquarters, he is now the controller for a regional sales unit of a consumer electronics company. He is excited about this step up and wants to build a good relationship with his new team. However, when the quarterly numbers come due, he realizes that the next quarter’s sales are being reported early to boost bonus compensation. The group manager’s silence suggests that this sort of thing has probably happened before. Having dealt with such distortion when he sat in corporate, Jonathan is fully aware of its potential to cause major damage. But this is his first time working with people who are creating the problem instead of those who are trying to fix it.

This may seem like a mundane accounting matter. But the consequences—in terms of carrying costs, distorted forecasting, compromised ethical culture, and even legal ramifications—are very serious. And except in extraordinarily well-run corporations, this kind of situation can arise easily. All managers should know how to respond constructively (indeed, learning to do so is a key piece of their professional development), and senior managers must be able to change the cultural norms that gave rise to bad judgment in the first place.

Over the past four years, I have studied the moments when people decide whether to speak up about an ethical issue, and what they say when they do. I’ve collected stories from managers at all levels, with a particular focus on the earlier years in careers and on individuals who have positive stories to tell. These stories—along with the social-psychology research on decision making—shed light on what enables people to be candid when they encounter ethical conflicts in the workplace. The insights I describe here can help younger managers raise their voices when they should and help senior managers build a strong, honest organizational culture.

Many Excuses for Silence
When a manager encounters an ethical problem, chances are he’ll also hear—or tell himself—one of four classic rationalizations for keeping silent.

It’s standard practice.
Jonathan will probably encounter this excuse when he questions his group’s quarterly sales report. Though this kind of distortion is common, that does not diminish the costs it can trigger, the fact it is unethical, or the dangerous ripple effects it can have on the business down the road.

It’s not a big deal.
When Maureen, a product-engineering manager at a computer systems company, learned that her group’s single-wipe process for reconfiguring hard drives was failing 5% of the time, she knew that some customers would end up with a reconditioned machine that still contained the previous owner’s information. But her colleagues argued that no one had complained, that it was unlikely to cause a problem anyway, and that no one wanted to take on the cost of resolving the issue in a time of budget cuts.

It’s not my responsibility.
You or your colleagues may be tempted to say that you’re too new in the job to chime in, that you don’t have the authority, or that you’re not the expert. Junior employees often get this message from others—but, I was surprised to discover, so do senior executives. For example, Denise, a senior vice president and the COO at a regional hospital, had a hunch that a trusted consultant was supplying her CEO with inaccurate financial analysis. She was afraid that, as a result, her boss would make a bad call about whether to sell the institution. This possibility weighed on her, because a sale would mean a host of problems for patients. She was new in her position, though; the CEO had brought her over from a nurse executive role, and she was still learning the ropes. She knew that the CEO believed in the sale, and she worried that her insights would not seem as credible as those of her boss’s expert adviser. Indeed, when she first broached the topic, the CEO dismissed her concerns and her right to play a role in the decision making.

I want to be loyal.
Many times people feel there is a conflict between doing what’s right and being loyal to their coworkers, manager, or company. Though this question of loyalty may at times represent a true ethical dilemma, it is often just a rationalization.

Jonathan, of course, faces this tension. Adjusting the quarterly sales report for his group will reduce everyone’s compensation bonus, and his colleagues may accuse him of disloyalty.

Here’s a higher-level example: Donald was chairman of the board of a high-technology firm whose senior executives had been caught in an options-backdating scandal. Even after he had taken all the steps that were recommended by external legal advisers—ordering a special investigation, dismissing the executives involved, bringing on a new director with a reputation for hard-headed integrity—the firm was still being pilloried in the press and struggling on Wall Street. So his advisers then argued for a clean sweep of the board, including Donald himself. Although he came to believe that his advisers were right, he worried that if he resigned and urged his colleagues to do the same thing, their reputations would suffer and they’d become targets for litigation. Fiduciary responsibility appeared to be pitted against personal loyalty.

Other excuses emerge, as well—for instance, time pressure—but they’re usually paired with one of the rationalizations above.

by Mary Gentile

~to be continued