Heating & Cooling

District heating systems provide economies of scale in large cities like Copenhagen.

Photo: Bill Ebbesen. License: CC BY 3.0.


Energy-efficient HVAC design is a fundamental of green building, for good reason:

  • The scale of the issue: HVAC is responsible for more than a third of energy use in commercial buildings in the U.S.

  • The scale of returns: Smart designs can easily save upwards of 40% of that energy, often with strategies that offer instant or short “payback.”

  • The human impact: Discomfort from spaces that are too hot or too cold, and lack of adequate ventilation, are an epidemic. Good design that fixes these problems supports healthier, more productive occupants.

Don’t make the all-too-common mistake of thinking of HVAC design separately from building envelope design. Over-glazed buildings lead to oversized mechanical systems, increasing costs on both fronts. A tight, well-insulated envelope may cost a bit more but can pay for itself with less mechanical equipment.

  • A Plug-and-Play Hydronic System that Captures VRF Waste Heat

    Product Review

    The LG Hydro Kit, now sized for residential and multi-family use, captures waste heat from its Multi V heat pumps to provide a fossil-fuel-free source of hot and cold water for space heating or domestic hot water.

  • Mag Lev Chiller uses Low-Global-Warming-Potential Refrigerant

    Product Review

    YORK YZ Magnetic Bearing Centrifugal Chiller is the first chiller to be optimized for use with a low-GWP hydrofluoroolefin (HFO) refrigerant.

  • The Cost of Comfort: Climate Change and Refrigerants

    Feature Article

    Refrigerants with very high global warming potential can negate the energy-efficiency benefits of many HVAC systems, including popular heat pumps.

  • Are Cool Roofs Green? The Answer’s Not Black and White

    Feature Article

    Roofing choices are complicated by heating tradeoffs, climate effects, and condensation, but proponents say reflective roofs still make sense in most climates.

  • Passive Solar Heating

    Feature Article

    Using the sun for most of a building's heating needs is in the DNA of green building. But in an age of superinsulation, does it still make sense?

  • Solar Thermal Hot Water, Heating, and Cooling

    Feature Article

    By creating heat instead of electricity, solar thermal achieves three times the efficiency of photovoltaics at a lower price.

  • Buildings on Ice: Making the Case for Thermal Energy Storage

    Feature Article

    Thermal energy storage uses ice to shift daytime cooling loads to nighttime, when electricity costs are lower. You may be able to reduce the size of chillers as a result, saving money and energy and lowering the environmental footprint of a building

  • Ductless Mini-Splits and Their Kin: The Revolution in Variable-Refrigerant-Flow Air Conditioning

    Feature Article

    Ductless split systems using heat pumps and variable refrigerant flow offer an energy-efficient alternative to conventional heating and air-conditioning systems for a variety of settings, from homes to hotels and schools. Three major manufacturers-Daikin, Mitsubishi, and Sanyo-offer the greatest variety of products.

  • The Challenge of Existing Homes: Retrofitting for Dramatic Energy Savings

    Feature Article

    Greenhouse gas emissions associated with residential energy use account for a fifth of all emissions in the U.S. Retrofitting existing houses to achieve a two- to three-fold reduction in energy use is necessary if we are to achieve the emissions reductions scientists say are required for avoiding catastrophic climate change. Here's a look at how it can be done.

  • In the Pipeline: District Energy and Green Building

    Feature Article

    Very common in northern Europe, district energy systems use a network of buried, insulated pipes to distribute centrally produced steam, hot water, or chilled water to heat or cool multiple buildings. These systems can make use of waste heat from power generation (combined heat and power) or renewable fuel sources to help reduce the environmental impacts of buildings and communities.