Maybe the old saying applies: If it sounds too good to be true, it probably is. We want and need “sustainability.” We want and need buildings, towns, and cities that are not bad for the environment nor the people who live and work in them. But is “new” the solution or the problem?

In the last 50 years, humans have used more raw materials and created more waste than in all previous history. The statistics about individual and worldwide consumption are grim, reminiscent of the image of Al Gore riding a scissor lift to emphasize the exponential increase in greenhouse gas emissions. The Environmental Protection Agency estimates that 42 percent of total US greenhouse gas emissions are associated with materials as they flow through the economy — from extraction, production, and transport to disposal. The single biggest consumer of materials? The built environment, which uses about half of all raw material extracts.

Every product, no matter how green, has environmental impacts that include carbon emissions, water and energy consumption, pollution, toxicity, and waste. To quote that great environmental steward, Pope Francis, “The earth, our home, is beginning to look more and more like an immense pile of filth.” Each year hundreds of millions of tons of waste — from mine tailings to lightbulbs — are generated through production and end-of-life disposal. Much of this is nonbiodegradable and toxic. Upstream industrial waste, created prior to product use, is estimated at anywhere from 20 to 90 times the material of the actual product. In the United States, two-thirds of all downstream waste comes from construction and demolition.

Toxicity is not limited to waste. Building products are under increasing scrutiny because of the inclusion of toxic chemicals, such as lead, formaldehyde, asbestos, chlorinated solvents, petroleum distillates, toluene, xylene, and PCBs. Like almost everything related to material consumption, the trends are not good. In a 2013 Brown University study, more than half of women of childbearing age had median or higher levels of at least two out of three pollutants — lead, mercury, and PCBs —  that could harm fetal brain development. The US Centers for Disease Control and Prevention has concluded that nearly 100 percent of US citizens have brominated flame retardants in their bodies. Flame retardants are applied to fabrics, carpets, building insulation, and electrical cables, among other things. During the last 30 years, the level of flame retardant chemicals in humans has increased by a factor of 100 — essentially doubling every five years. These chemicals are linked to dna mutation, thyroid disruption, memory and learning problems, delayed mental and physical development, lower IQ, advanced puberty, and reduced fertility.

The good news for designers is that toxicity is becoming a highly visible issue. Thanks to the leadership of organizations such as the US Green Building Council, Building Green, the Healthy Building Network, and the Living Futures Institute, information about materials is easier to obtain. But even with more transparency about what is in a product, preservation professionals are probably leerier than most about new materials in general. Many of us have spent our careers removing the miracle products of the past, which are now deemed toxic. It’s estimated that only 2 percent of existing chemicals are tested for carcinogenicity. We can only wonder, as new information comes to light, which miracle products of the present will be removed in years to come and where they will go.

Removing toxicity, although obviously important, doesn’t address the often hidden costs of pollution, waste, and worker illness created during extraction of materials, their production, and their transportation. Nor does it change the greenhouse gas emissions that happen at every stage of the process. It seems almost fashionable in the design and construction world to focus on the operation of buildings when discussing how bad they are for the environment. We cannot count the number of presentations we have sat through that make the claim that the greenhouse gases released or the energy used to make all the parts of a new building will ultimately be paid back many times over by the amazing new energy efficiency achieved in operations.

Skepticism reigns when we hear this because the argument misses important points: Environmental degradation is not just about greenhouse gases; water consumption and social equity issues in manufacturing are largely being ignored; many buildings (however green the claims) are car-dependent, oversized, and do not achieve the energy-efficiency goals claimed. Most important, this is a critical moment in history, as the rapidly increasing population of the planet begins to acknowledge the magnitude of climate change and our role in promoting it. We need to be selective about actions contributing to greenhouse gas emissions right now.

There is no question that new construction creates an immediate emissions deficit while the payback period is calculated in decades. A 2012 report by the National Trust for Historic Preservation, in partnership with Skanska and the Cascadia Green Building Council, found that it can take between 10 and 80 years for even an energy-efficient new building to overcome, through cleaner operations, the climate change impacts created by its construction. These are precious decades we cannot afford.

“Less is more” should be the order of the day. What are the actions that gain the best returns on resource consumption with the least expenditure? At the moment this is not a financial calculation. The direct costs of products, energy, and water do not reflect environmental impacts. This must change.

Clearly, new construction is not going to stop, and conversations analyzing how to reduce the climate impacts of structural systems — concrete and steel, which are the biggest culprits in emitting greenhouse gases — are increasing. We are striving to make our new buildings less bad, but we also should be striving to preserve what already exists.

Extending the service life of any object avoids the environmental impact of replacing it. To extend the life of buildings, regular maintenance is required, but this is hardly the norm. In the institutional and nonprofit world, fundraising for maintenance is exceedingly difficult. Having a new building or space named after a donor is much easier to sell than the Jane Doe Repair Plan. For government and private owners, maintenance is often the easiest budget item to cut, kicking the cost down the road. All too soon it becomes easier to replace than to repair. The new building might even achieve top billing for its healthy materials and net-zero-energy consumption.

The reality is that we will probably never be able to completely negate the environmental impact of products nor ensure that every new building will meet the regenerative aspirations of the Living Building Challenge, which calls for the creation of building projects to operate as cleanly, beautifully, and efficiently as nature’s architecture. Even if we could, doesn’t a sustainable world need to value what already exists not only for environmental reasons but also to foster creativity, social engagement, and a unique sense of place?

In The Death and Life of Great American Cities, Jane Jacobs observed that “Cities need old buildings so badly it is probably impossible for vigorous streets and districts to grow without them.” The Preservation Green Lab, which is part of the National Trust for Historic Preservation, produced a 2014 report — “Older, Smaller, Better” — which provides the most complete empirical validation to date of Jacobs’ long-respected but largely untested hypothesis: that neighborhoods con­taining a mix of older, smaller buildings of diverse age support greater levels of economic and social activity than areas dominated by newer, larger buildings. Tested against 40 economic, social, cultural, and environmental performance metrics, the findings support the idea that retaining blocks of older, smaller, mixed-vintage buildings can help cities achieve sustainable development goals and foster great neighborhoods.

Radical common sense requires moving past our throwaway culture to a regenerative world that creatively and persistently embraces stewardship. The path to a healthy, sustainable world is complex and certainly not linear, and it may never be fully achieved. But we cannot consume our way to sustainability. We must flip this dangerous paradigm and place real economic and social value on what already exists and the stewardship required to maintain it.