Sustainable Heating and Cooling: Digging The Foundations

Dec 28, 2009

Beginning to take conservation seriously, society is shocked by the data on energy waste. Nowhere is this truer than in the way we heat and cool dwellings.

For generations, back to electrification, our knowledge of home energy use was masked by dial thermostats that helped us to be comfortable but hid most of the cost. In recent years, programmable thermostats, conservation-minded but hard for most of us to use, have begun to replace the simple dial.

What this "comfort" thermostat has hidden from us is that buildings account for 40% of our energy use and HVAC (heating, cooling and ventilation) 56% of that, that the leaks in most buildings make their HVAC work harder, that HVAC systems themselves are energy hogs, and that most are badly installed or maintained, to the extent that duct leaks alone make them run on average 20% less efficiently in our dwellings than they do in manufacturer's tests.

Nor has the comfort thermostat taught us the environmental cost of our habits: that all our air conditioners running in tandem cause utilities to use their most CO2-laden energy sources, for example. Nor did it tell us that most utilities, until recently tasked only to deliver all the energy we want, were happy to facilitate this wastefulness.

Fortunately, in recent years some public and non-profit entities and some companies have gotten a start toward energy efficient HVAC. And these seeds are about to sprout — provided that the public will, translated into laws and public investments, can be brought along. But it isn't close to clear that efficiency politics well win (see Copenhagen). Our tragically high degree of heating, cooling and ventilation waste could ride a long plateau or even worsen.

Thus this energy efficiency story, like all others, is one of advocacy, technologies and consumers.

Faulty Towers

On Jan. 1, the programmable thermostat, used to tell an HVAC system when it can regularly reduce its load (for example, in the hours when a house is usually unoccupied), will lose its Energy Star ratings. Manufacturers will have to remove the Energy Star logos from their product boxes. EPA is forcing this change because research shows that most people can't figure out how to use them right.

Thus, 2010 begins with a big if temporary defeat, for mitigation advocates and for businesses. Absent the Energy Star logo, will these products that add extra cost find buyers?

HARDI, the HVAC distributors trade association, wrote to the EPA in November:

"Preventing the industry from providing an Energy Star labeled product for the most seen and recognized aspect of any HVAC system threatens to erode consumers' perceived value of the multi-thousand dollar Energy Star HVAC system they just installed."

Which makes us ask what Energy Star HVAC systems are and how they came about. We again start with energy waste in the system, which as energy prices rise will be wasting money, as well. The inefficiencies begin upstream from HVAC, in the building envelope, in its insulation, windows, and doors. But this is a story in its own right.

Green building materials are being developed, "holistic" home energy auditing tactics are emerging, a $23 billion "Cash for Caulkers" program is being promoted by the Obama team, and the problems associated with fixing 110 million existing residential building envelopes, each built and maintained in idiosyncratic ways, are astounding.

The HVAC industry, manufacturers and a sales and services channel, has always accepted wasteful envelopes, as it accepted low energy costs, and it accepted its own role being to provide space comfort without regard to waste.

Thus, its business practices formed around what is called a "least first cost" model: Build and sell inexpensive systems and ignore the leakage and wasted energy. With energy costs low (and with the reasons for this hidden, if in plain sight), uncomfortable people could just mask the system waste and inefficiencies by cranking the heat higher or lower. Which is a nice snapshot of what, writ large, has gotten us in this grand climate change mess.

Public Advocacy

With consistent nudges as well as consulting help from non-profit energy efficiency advocates, especially CEE (The Consortium for Energy Efficiency) and ACEEE (American Council for an Energy Efficient Economy), the EPA and some state environmental agencies, particularly California's, began a march two decades ago to sustainable HVAC.

The work began with improving the mechanical system components. Issue by issue, efficiency advocates, working often with industry partners, looked for new technology solutions. A geeky example is dual-staging, a way to let a system run at half power when that does the job. Triple-stage components, cutting energy usage and costs by two-thirds some of the time, are in the marketplace now.

EPA's practice is to aggregate new efficiency technologies into new Energy Star standards. About once a decade, it raises the minimum standard that products for sale must meet. In 2006, SEER 13 became the minimum residential HVAC standard. The sum of its new technology was to reduce power usage 30% over the prior SEER 10 standard. Meanwhile some in the HVAC industry continue to innovate. Advanced, high price systems that rate SEER 25 or higher have reached the marketplace, even if sales are small.

In September 2009, ACEEE and a dozen other non-profits and state agencies signed a long-negotiated agreement with AHRI, the HVAC manufacturers trade association, in support of a more efficient set of federal standards:

"Between now and 2030, the agreement will save 3.7 quadrillion Btu of energy nationwide, equivalent to the energy consumed by 18 million households in one year. ... It will raise the minimum efficiency of residential central air conditioning systems by 8 percent and furnaces by 13 percent, and result in a 5 percent reduction of the total heating energy load and a six percent reduction of the total cooling energy load in 2030."

In California, where energy efficiency is a mandate, the 97-page Building HVAC chapter of the Title 24 (signed in 2008, to take effect in 2011) Residential Compliance Manual creates minimum efficiency requirements for every kind of HVAC component. Even more convincingly, it recognized the scope of the sustainable HVAC challenge by going beyond detailed component standards—such as unique rules for air conditioners with, and without, louvered sides.

The holistic eye it casts on what the private sector would call the entire HVAC value chain goes from efficiencies in products to finding solutions to the ineffective ways in which the products are installed and then maintained. So it is challenging the habits of not just consumers and manufacturers but also of a mostly mom-and-pop service industry.

Therefore, the California Energy Commission (CEC), with its counterparts in a few other states, Obama's DOE, and some industry participants, is putting muscle behind an effort to move an entire product ecosystem from a long held model of sell it and forget it (least first cost) to a new one of achieving least total cost via end-to-end efficiency.

110 Million Service Calls (Oh, My!)

Noting that the rising size of houses and the percent with central AC has led to HVAC accounting for 25% of peak power usage in 2009, up from 6% in 1979, the CEC attacked installation and maintenance. It wrote new standards, made utilities and manufacturers invest in solutions, and funded R&D.

In the space (no pun intended) between building envelope inefficiencies and the remaining inefficiencies in the newer SEER components is the problem area of HVAC integration. All of the components may be good or even best quality, but if they aren't sized right or don't match, or if the refrigerant charge or the air flow isn't rightly calibrated, or if the ducts leak or aren't sized right, then from some to most of the energy that the HVAC system uses just leaks outdoors.

On average today in the U.S., integration issues cause 75% of the total energy waste (meaning that the highest SEER components can only improve the overall efficiency 25%).

Most systems in houses today were either installed or are being maintained ineffectively, or both. Best practices are being developed, but they contend with the least first cost model of the service industry. In California, 90% of HVAC installations occur without the contractors either pulling permits or having the systems inspected. Few consumers know how well their HVAC is working.

Because nationally there are 20,000 HVAC contracting businesses, more than half with fewer than eight employees, and because nearly all of these small businesses take any work that they can get, working on all kinds of systems, there is, in addition to an ingrained least first cost problem, a daunting service education problem.

The DOE, some states and efficiency advocates are, again, working on these integration issues, as are trade groups and private companies. The issues split, though, into solutions and enforcement. Like the AHRI standards, the 2007 standards developed by a stakeholder team led by ACCA (Air Conditioning Contractors of America) for quality HVAC installation (QI) and maintenance (QM) are voluntary — contractors can use them or not as they choose.

Both the QI and the QM manuals combine prescriptive statements (a little boring for those not in the game):

"The contractor shall ensure that heat loss and heat gain load calculations are performed for every HVAC system installation or replacement ... shall verify that the airflow across the indoor heat exchanger is within acceptable ranges... shall ensure the ducts are sealed and that air leakage is minimized."

With specific requirements and directions (more boring still):

"For cooling coil (e.g., refrigerant, water) and heat pump applications 1: Airflow across the coil, at fan design speed and full operating load, is within 15% of the airflow required per the system design. And II: Airflow across the coil is within the range recommended by the OEM product data."

The manuals cover heating, cooling, ventilation and humidity and provide detailed requirements for different kinds of systems (like gas or electric heat) and different kinds of buildings. Their intentions are to spell out for the first time how to detect and solve problems. But because most dwellings and small commercial spaces have unique HVAC installations, usually the result of tweaking done over decades, often by multiple generations of owners, contractors need training and experience to get much actual help from the manuals.

The QI manual, in fact, requires HVAC installers to complete a 12-hour North American Technical Excellence (NATE) course each year. But as reading the manual is itself voluntary, its requirements are only guidelines.

The inefficiencies of the service sector and the barriers to its changing have led to attempts to require mandatory QI and QM standards, so far unsuccessful, and to efforts to use information technology (IT) to help contractors and customers. IT use has been driven by public sector actors, CEC and NIST (National Institute for Standards and Technology). This early stage work borrows from the control systems used in large commercial buildings.

A name applied to this work is "Fault Detection and Diagnosis." It anticipates home HVAC components having computer intelligence and network communications, neither of which they have now outside of a few advanced systems. During installation and as a maintenance procedure, the network would poll its components for faults. The network might then, for example, detect or even precisely analyze a duct leak or a refrigerant problem. IT diagnostic tools of this kind have been used in other industries for decades. They could help installers qualify their QI and QM procedures. They could help consumers know and improve the efficiency of their systems.

Looking ahead to 110 million house calls, this HVAC repair job will need all the diagnostic help it can get.

Summoning Public Will

This work making how we heat and cool dwellings energy efficient is ahead of the work, also beginning, to achieve further efficiency by integrating HVAC with the smart grid and utility demand response programs. And yet, none of this can go forward to scale without a political will for efficiency. This would translate into new laws, codes and public investments — into mandating things now voluntary, like a NATE course of training for every contractor.


See also:

Smart Grid: Digging The Foundations

Electric Energy Storage: Digging the Foundations (Part I)

Electric Energy Storage: Digging the Foundations (Part II)

New Business Model Cuts Up-Front Costs to Spur Energy Efficiency

Climate Legislation Could Be a Catalyst for Energy Efficiency

LEED No Longer Stops at Construction: Version 3 Checks Up on Efficiency


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