Recently in Roofing Category

Many homes have moisture, combustion safety or indoor air quality problem that result from inadequate or non-functional energy systems.

• It is estimated that 40% of basements in Canada are damp and for children, the health effect of living in damp environments is equal to exposure to secondhand smoke (Fugler 2007).
• One in 15 homes in the US has elevated radon.
• 64 million homes have lead-based paint somewhere in the building.
• Over 20 million Americans have asthma and in 1990, asthma was the cause of 4500 deaths annually.  Many asthma triggers are found in indoor environments.

Energy improvements can potentially exacerbate or create new problems as well as fix existing problems.  We need a trained workforce to properly install energy efficiency projects.

Information and misinformation abounds and is often contradictory.  This can be overwhelming for home owners.

In many cases, true efficiency improvements are not the function of mere presence of a high efficiency product -- but rather, its appropriateness and correct installation.

Certification and quality assurance programs offered by organization help support a trained workforce.  These organizations offer programs:

• NATE
• BPI
• ACCA
• EPA Home Performance
• Energy Star

Three paradigms influence residential energy efficiency efforts:

1. the products
2. whole house or home performance
3. sustainability strategies

Product Rebate Programs

Products that sport rebates for high-efficiency models such as Energy Star rated appliances, CFLs, LEDs and high performance air conditioners can lower product costs and increase adoption.

Rebate programs can ramp up quickly, are easy to deploy, and fairly easy to evaluate.  While widget-based rebate programs have relatively low savings per unit, the high nuber of units and low per-unit transaction cost can yield significant and cost-effective energy reductions, particularly if the market is truly transformed after the removal of the incentive. 

One problem of rebate programs is that they usually do not address site-specific selection/application, installation, measure interaction or deal with side effects.  Because of these limitations, rebates can sometimes result in lost opportunities for more significant alternatives and create negative side effects.

Home Performance Programs
 
The whole house or home performance paradigm focuses on building system performance ith energy reduction as one part of the greater whole.  To date, whole house programs have mostly been delivered through low-income programs and are beginning to filter into for-profit energy efficiency programs. 

Typical costs range from $3-$35,000 per house; and energy reductions range from 5-35%.

A home performance job may include work and cost tht is directed to solving problems such as correcting a wet basement or crawl space, which may not generate direct energy savings.

Sustainable Paradigm
Current and long erm impact on the community and larger environment are considered in a sustainable paradigm that assesses the life cycle of building components and products consumed in house operation.  Land use, water use, and site environmental impact, as well as building durability and energy use are examined.  This is a "green building" approach.

Interest in USGBC and ASID's green guideline for existing homes, REGREEN, released in 2008 has exceeded the expectation of the developers (Yost 2008).

Deep Energy Reduction Paradigm

The deep energy reduction paradigm builds on the strengths of the previous paradigms.  The deep energy paradigm fits well in a sustainable paradigm that incorporates a design centered approach and inclusion of impacts beyond the homeowner's site.

While many strategies can be used to achieve deep energy reductions, universal principles are emerging.  To summarize them:

• A systems approach is necessary to optimize on-site and off-site benefits and interactions
• Good indoor air quality and building durability are integral elements
• Performance must be verified with a combination of diagnostic equipment and actual measurement of all benefits.
• Occupant behavior and community solutions are an integral part of the strategy
• Deep energy reductions should be viewed as an ongoing process to ensure proper maintenance and operation
• A trigger event can capture opportunities as they emerge, ie: roof, siding or HVAC system replacements.

It's important to identify and target communities or situations that offer the combination of lowest costs and/or greatest benefits, access to resources and motivated occupants.

SOURCE:  Linda Wigington, Affordable Comfort, Inc; "Deep Energy Reductions in Existing Homes; Strategies for Implementation"

Strategies for net zero energy vary by household, climate, region and housing type.

Passive House Institute

The passive house standards in Germany and Austria have demonstrated that performance and cost savings can result when peak heating loads are reduced significantly.

Building Sciences Corporation completed a comprehensive renovation of a 100 year old home that resulted in a 60% energy savings while increasing the living space by 80%. (Pettit 2008)

Energy Efficiency Strategies That Work

A deep reduction approach with comprehensive insulation and air sealing can make a conventional furnace and air circulation system unnecessary, thus using simpler technical solutions to combustion safety distribution systems, durability and indoor air quality.

A deep energy retrofit could eliminate a conventional chimney, furnace and attic ductwork and replace these building elements with a mechanical ventilation system that manages indoor air quality and moisture control.

The Canadian Mortgage Housing Corporation (CMHC) recently published a study, "Approaching Net Zero Energy in Existing Housing" and concluded that climate, housing stock, energy loads, solar gain and occupant behavior all contribute to the feasibility of reaching net zero energy use in existing homes.   With no incentive available, it is not cost effective to achieve net zero energy in most Canadian housing.

Energy Efficiency Justification

Solving problems with wet basements, radon, outdated mechanical equiment and inadequate indoor air quality can help justify energy efficiency choices.

Reducing heating loads is relatively easy.  It is more challenging to achieve deep reductions in baseloads and cooling loads which are more dependent on occupant behavior and lifestyle.  Motivated occupants are essential.

The California energy crisis of 2000-2001 resulted in a 15% reduction in electrical energy use that was primarily the result of occupant behavior, not technology.  The actions of a small number of supersavers and modest efforts by many residents were deemed responsible for the reduction.

Utility programs can substantially reduce energy use with energy efficient features such as low-e windows and building enclosure improvements that focus on reducing air infiltration and upgrading insulation performance.  Also helpful are replacement of heating nd cooling systems, duct leakage reduction, and use of other controls for electrical and cooling loads.

Community Solutions

Homeowner choices sometimes affect lifestyle choices significantly.  Possible strategies can include use of renewable energy supply or a change in the use of space or the number of people in a home.  Highly effective choices can include co-housing with efficient shared cooking, water heating, clothes washing and entertainment facilities.

Reduce the Load First

Marc Rosenbaum suggests a simple maxim, "Invest as much as you can afford to reduce the load, even if it means completing a project in phases."  These load-reducing options that can help achive optimum results are major systems such as siding and roofing. 

Choices for Thermal Comfort

Thermal comfort accounts for 25 - 80% of residential energy use.   Some of the options available include:

Community Solutions

• Comfort centers
• Cogeneration or micro-cogen
• Community thermal storage
• Community-based renewable energy supply
• Use of waste heat from industrial processes
• GHG reduction campaigns
• Feedback, benchmarking, aggregation
• Competitions and challenges
• Technical, financial and regulatory support

Behavioral Choices

• 24/7 set point adjustment or setback
• Apply comfort zone
• Change use of space with new thermal boundaries
• Adaptive comfort (clothing, surface temperature, air movement)
• Increase occupancy
• Reduce internal gains with behavioral cooling loads
• Decrease occupancy size with relocation or demolishing space

Technical Solutions with Higher Cost

• Superinsulation (walls, ceiling, floor, foundation - climate specific for R25-R80)
• Efficient windows  (U 0.1 to 0.3)
• Super air tightening  (0.2 CFM/ftx2 floor space)
• High efficiency mechanical ventilation
• Ultra high efficiency HVAC system
• Automatic movable window insulation
• Highly insulated doors

Technical Solutions with Lower Cost

• Fill cavities with insulation
• Air sealing
• Do-it-yourself superinsulation
• Seal / insulate attic ducts or eliminate ducts
• Point heat or cooling source
• High performance storm windows
• Manually controlled movable window insulation
• Reduce internal gains with technical fix of cooling loads
• Control systems to optimize comfort, indoor air quality and humidity

On-Site Renewable Energy

• Increase solar gain through windows
• Sunspace or solar buffer to reduce heat loss
• Active solar thermal
• Solar PV
• Wood heat
• Trees vegetation or other shading to reduce cooling loads