New Old AC Technology

Old ideas combined with new material technologies may provide huge energy savings from a different type of air-conditioning system.

A typical air conditioner cools the air and dehumidifies it all at once, but not in a controlled way. The limit to how much drying can be achieved depends on how much water condenses on the evaporator coils as the air passes through. This so-called "wet-bulb limit" is the reason typical evaporative coolers either can't cool things down enough or can't create a truly comfortable space when there is a lot of heat and humidity in the air.

By contrast, DEVAP can provide cooling in any climate. The first stage wrings out all the moisture in the air. Doing so lowers the effective temperature limit the indirect evaporative cooler can achieve. It has a wet-bulb effectiveness of 125% — a huge boon compared to most current technology that has tried to get as close as it can to 100%.

DEVAP has several other advantages over conventional cooling, including:

• There is no need for environmentally damaging working fluids such as the chlorofluorocarbons, hydrochlorofluorocarbons, or hydrofluorocarbons used in vapor compression systems.
• The working fluids in DEVAP are environmentally benign: water and a strong salt solution for the desiccant.
• DEVAP allows independent control of temperature and humidity, something that is not possible with conventional A/C unless an expensive overcooling and reheating process is employed.
• There is no need for a compressor or large amounts of expensive copper coils.
• DEVAP contains fewer moving parts in the form of simple low-pressure pumps and fans.
• Vapor compression A/C has been incrementally improved for over 100 years, so there are few low-cost energy improvements left for that technology.
• As efficient as DEVAP already is, there is lots of "thermodynamic room" for cost-effective efficiency improvements.

Green Resources

+ Building America
+ BuildingGreen.com
+ Certified Green Professional
+ Clean Air - Cool Planet
+ CTSI - Clean Technology
+ Ebay.com Green Team
+ EnergyStar
+ Environments for Living
+ Global Green
+ Green America
+ GreenBiz.com
+ Green Builder Magazine
+ Green Building Advisor
+ Green Building Initiative
+ Green Building Pro
+ Green Home Builder Mag
+ Green Home Guide
+ Happy Planet Index
+ Home Energy Saver
+ MyFlorida Green Building
+ Natural Home and Garden
+ Orange County Yards
+ Sustainable Buildings Ind.
+ Sustainable Site Initiative
+ Think About Pollution
+ US Dept. of Energy
+ Water Footprint
+ Winter Park Green Button
+ Winter Park Sustainability

Energy Resources

American Council on Energy
American Solar Energy Society
Consumer Energy Center
Energy and Environmental Building
EnergySavers.gov 
EnergyStar
Florida Energy and Climate Comm.
Florida Renewable Energy Assoc.
Florida Solar Energy Center
Florida Solar Energy Industries
FPL Energy Services
Home Energy Magazine
National Renewable Energy Lab
Progress Energy
Southeast Energy Alliance
US Department of Energy

Design Priorities for Energy Efficiency

Energy efficiency starts with good design. Of course the efficiency of nearly any home can be improved, but designing for energy efficiency is always going to yield the best results. 
Depending on the status of your project, there are priorities to consider that will have an impact on the energy performance of the structure.
    1. Property Selection - View lots are the most common to create challenges with home energy use. Ideally southern views are going to be beneficial and western views the most detrimental. Additionally the shape of the lot can affect the length axis of the home with positive or negative effects on energy use.
    2. Solar Orientation - Once property has been selected, the structure should be oriented to capitalize on the seasonal arc of the sun. In the northern hemisphere it's preferred to orient windows to the southern exposure and prevent heat gain on the east and west elevations.
    3. Passive Solar Design - The sun can heat our homes in the winter and even help keep us cool in the summer - for free, when passive solar design techniques are used. In this approach, the building itself or some element of it takes advantage of natural energy characteristics in materials and air created by exposure to the sun. Passive systems are simple, have few moving parts, and require minimal maintenance and no mechanical systems.
    4. Reduce Energy Demand - Some of the most effective methods to reduce energy use include: increased insulation values and weathertightness; HVAC zoning and programmable thermostats; CFL and LED lighting; and behavior modification.
    5. Increase Efficiency - Increased energy efficiency is available for a number of building systems. This is where cost-benefit analysis becomes important. Depending on the success of the previous strategies, there may be a point of diminishing returns from the investment in higher performance products. Windows and HVAC systems are the main items to fall into this category.
    6. Solar Thermal Heating (and Cooling) - Solar hot water heating is a type of thermal heating strategy but did you know that thermal solar collectors can also be used to heat the inside of the house? This is called hydronic heating and is actually quite comfortable and can be affordable. Additionally, in the right application solar thermal panels can actually be used to cool your home in the summer time.
    7. Alternate or Renewal Energy - The final upgrade to consider is the addition of an alternate energy source like photo-voltaic panels or a renewable source like a micro-hydro generator. Recent industry articles indicate the cost of PV (photo-voltaic) over their lifetime, is getting close to power purchased from utility companies. Additionally, if PV panels are amortized over a 15-year mortgage period, the cost saving and interest tax deduction may exceed the cost of purchased power. Let us help you make the calculations.

What Makes It Green?

Green can mean something a little different to everyone:  To some it may be features added to a home that increase its efficiency or improve the air quality; To others it may be more of an attitude, a feeling of responsibility or a lifestyle choice; And some may see the long-term value in quality, sustainability or reduced maintenance. The common perspective to all is foresight.

Good building science is green. Lessons from building science have taught us how to save energy; create healthy and comfortable indoor environments; and to use products and techniques that require less maintenance and last longer.

Good planning is green. With a little planning we can select products that save money and protect the environment; design a landscape that needs less irrigation water; learn how to recycle waste instead of sending it to a landfill; and utilize the sun's path to heat our home in the winter and avoid the heat in the summer.

Good stewardship is green. When we hire local craftsmen or purchase products that are manufactured nearby; control stormwater runoff and plant native species; and redevelop a property or utilize existing utilities, we are making decisions that are in the best interest of the environment or our communities.

There are tangible advantages to going green. Green can save energy, water and resources while improving the health, comfort and sustainability of our homes. But green is also an attitude. Our actions can go beyond personal benefits and affect the lives of those around us. Green feels good.

Building Science

Building Science is the study of buildings and construction techniques as they apply to the performance and sustainability of the structure. Many of the products and techniques associated with green construction are considered good building science.

The housing construction industry ranks among the worst in research and development. The independent nature of small builders combined with market pressures, have previously put the science of building at a low priority level. Rising energy costs and interest in green construction, have fueled the interest to learn a little more. 

Additionally, it's apparent that many consumers are demanding higher quality and performance from their builders. Recognized performance standards and third-party inspections are becoming the norm rather than the exception. Assurance that the structure and its systems are sustainable and performing correctly, has only been recently offered within the industry. Prior to recent awareness, there was no means for the consumer to really know what they were purchasing.

The Green Certification Process

Each of the green certifying programs uses similar checklists for tracking the green components of a home and calculating the overall performance rating. In general "Green" can be categorized into: 

• Property Characteristics; 
• Site Development; 
• Water Conservation; 
• Energy Efficiency; 
• Smart Resources; 
• Durable Construction; 
• Indoor Health; 
• Environmental Awareness; 
• Waste Management; and
• Operations and Maintenance.

Each comprises several methods of varying values that meet the intent of the category. The process is an integrative whole-building approach where points earned in one category may benefit or impede performance elsewhere. 

A preliminary analysis can be performed during the home design phase so that goals can be established for development of the project. Some of the most cost-effective and beneficial results can be obtained by incorporating green decisions into the early design phase. 

Green vs. Sustainable

Perhaps you've heard the term Sustainable used in conversation about Green construction. Like Energy-Efficiency or Water Conservation, Sustainable Construction is an aspect of many Green homes. But a home doesn't have to be green in order for it to be Sustainable.
Sustainable Construction refers to the aspects of a home that contribute to its long-term use. Products used within a home that have a long lifespan are sustainable. Likewise a product or feature is sustainable if it requires less maintenance or if can be recycled at the end of its life.

Sustainable construction focuses on minimizing the impact that buildings have on the environment with a key emphasis on durability and longevity. If a home is built to last a long time, additional resources won’t be needed for repair or remodeling. Sustainability saves money and reduces the time spent on maintenance; side benefits that everyone likes. 

Has the Term "Green" Been Over-Utilized?

I've occasionally observed confusion and resistance surrounding conversations about green construction and lifestyles.  I wonder why some people stumble while others are jumping on the green bandwagon, so I’ve decided to remove “green” from the discussion.  Here’s a list that I compiled of potential benefits related to the design, product selection and construction techniques that might be considered when planning a new home or renovation project:

• Community Impact
• Durable Construction
• Energy Efficiency
• Environmental Awareness
• Health and Comfort
• Operations and Maintenance
• Property Characteristics
• Resource Utilization
• Site Development
• Waste Management
• Water Conservation

What factors do you use in the decision-making process? 

LEEDigation and the Real Risk of Building Green

LEEDigation is a new term used to describe “green” litigation related to the apparent failure of some building projects to meet green performance standards. Legal discussions highlight the risk taken by builders that agree to obtain a level of green certification but fail to perform as expected. In the referenced case, arguments ensued because the construction specifications prescribed methods and materials that did not meet the performance standards necessary to obtain the “green points” required for the certification. The project failed to meet energy performance requirements and deadlines that would have qualified it for substantial tax breaks and incentives. (Shaw Development vs. Southern Builders)

The contractor had agreed to meet a silver level of certification but argued that the specifications for the project prescribed products, materials and methods that were contrary to the performance goals. The contractor had foolishly agreed to meet performance goals without control of the specifications that would enable the completed project to perform as required. Actually, this is not a green issue but a lesson about the difference between prescribed and performance standards. All said, the potential for LEEDigation has many contractors wondering how to protect themselves.

The real risk in building green is the failure to meet expectations of the project requirements. What happens when green point requirements are overlooked or the proper verification and documentation is missed?

Strategies to avoid LEEDigation:

• Define clear responsibilities of Architect, Builder and Owner.
• Avoid  performance requirements.
• Establish clear prescriptive requirements (specifications).
• Develop a timeline and checklist to avoid omissions (schedule).

Green building and renewed interest in energy efficiency pose new challenges to the construction industry, typically slow to change its thinking. Not only do we need to update our processes to include the added steps required by green certification, but we also need to update our understanding of building science and integrated building systems; another interesting topic for discussion.

AC Ducts in the Attic

The Greenhouse Effect causes a typical attic to become super-heated in the summertime. For this and other very important reasons, we now realize that AC ductwork doesn’t belong in a typical vented attic. After 50 years of installing AC ducts in the wrong place, why are we just realizing this now? 

First a little history lesson...

In 1947 mass-produced, low-cost window air conditioners became possible as a result of innovations by engineer Henry Galson, who set up production lines for a number of manufacturers. That year, 43,000 window air conditioners were sold in the United States. By 1969 more than half of new automobiles were equipped with air conditioning and most new homes were built with central AC.
(Ref. National Academy of Engineering. www.greatachievents.org)

In 1952, in Pompano Beach Florida, the metal plate connected engineered wood truss was invented and patented. The invention marked the beginning of the truss industry, that is still dominating building construction all over the world. (Ref. www.truss-frame.com )

It’s interesting to note that nearly all of the renowned Florida architectural styles pre-date World War II. After costs doubled during the 40’s and early 50’s because of increased cost of labor and materials, many new homes were downsized and simplified.  These modest homes proliferated across the American landscape. It was an extremely significant time in our country’s history with returning veterans from World War II and the Korean War, creating a huge need for simple, secure housing. Tract home communities sprang up across the country, and the suburbs were quickly filled with new homes - all part of the American dream.
(Ref. www.floridahistorichomes.com)

Additionally during this time period, mass-produced concrete blocks became readily available and spurred the growth of Florida concrete industry giants, Rinker and Florida Rock. At the time concrete block seemed like an ideal building material to fill the need for low-cost housing also fueled by population migration into the state. Hence, the now well-known basic Florida construction style developed: slab-on-grade; concrete block walls; and engineered wood trusses for the roof structure.

Since most homes in Florida were built without basements, the attic became a convenient place to install the AC ducts. Energy was cheap and air-conditioning was a welcome necessity, so until recently AC ducts have been going into a typical attic and few builders and designers ever considered otherwise.

There was a brief interest in increased energy efficiency after the OPEC oil embargo of the 1970’s, but it quickly faded as the affluence and growth of the American economy influenced the purchasing decisions of home buyers and builders. In another post, I’ll discuss how this same affluence has degraded building performance and brainwashed the consumer into comparing homes using cost-per-square-foot analysis.