A police lineup of climate change offenders would likely contain the usual suspects of automobile tailpipes, smokestacks, manure pits and the like. But buildings are egregious offenders, too, and that’s prompted a new kind of exchange-traded fund.

The Invesco MSCI Green Building ETF (GBLD), which launches today, is billed as the first ETF focused on the so-called green building ecosystem. The fund tracks the MSCI Global Environment Index, made up of companies that design, build, redevelop or retrofit green-certified buildings. The index also includes third-party entities that bestow green-certified status on properties.

The fund’s five environmental themes consist of alternative energy, sustainable water, green building, pollution prevention and clean technology. Companies in the index must get at least 50% of their revenue from environmentally beneficial products and services.

Green-certified buildings have been a thing for a while, and for good reason. According to the United Nations Environment Programme, non-residential and residential buildings, along with the building construction industry, produced 38% of global carbon emissions in 2019.

Closer to home, a 2018 report from the nonprofit Center for Climate and Energy Solutions said that fossil fuels consumed by residential and commercial buildings contributed about 29% of total U.S. greenhouse emissions, even as increased energy efficiency reduced residential emissions by 17.3% and commercial sector emissions by 11.4% since their 2005 peaks.

Still, the report cautioned that the growing use of appliances and electronics will boost energy consumption and could produce a net increase in building-related greenhouse gas emissions by 2050. (For example, there will be a greater use of air conditioning as more people relocate to warmer climates.) Hence, there’s a need to moderate that expected increase by making properties as eco-friendly as possible.

The GBLD fund comprises a global portfolio dominated by real estate investment trusts—nine of the top 10 positions are REITs. That includes Boston Properties Inc., Vornado Realty Trust and Kilroy Realty Corp. in the U.S., along with overseas holdings Unibail-Rodamco-Westfield, Nippon Building Fund Inc. and the Berkeley Group Holdings PLC.

Its net expense ratio of 0.39% is much less than the fees charged by two other successful Invesco products with an environmental bent: The $3.1 billion Invesco Solar ETF (TAN) charges a 0.69% fee while the $2.1 billion Invesco WilderHill Clean Energy ETF (PBW) charges 0.70%.

Climate change is probably the defining issue of our time and, as such, is likely a winning investment theme over the long haul. But these two existing Invesco products show that funds focused on this concept will have their mood swings. The solar ETF gained a whopping 234% last year but it’s down 17% year to date, while the clean energy product leaped 204% last year but has dropped 15.5% this year.