Courtesy : healthcaredesignmagazine.com
Climate change design
Additionally, organizations are asked to publicly report on their progress, complete an inventory of supply chain emissions, develop climate resilience plans for their facilities and communities, and designate an executive lead for the work.
The reason, stated simply, is that healthcare buildings, especially hospitals, consume a lot of energy—twice to more than four times as much as the typical commercial office building and as much as 10 times the typical primary school.
Hospitals burn fossil fuels through on-site combustion, releasing carbon dioxide (the most common human activity-caused GHG) as a product of that combustion, mostly to produce space heating.
Hospitals also consume electricity, which indirectly causes carbon dioxide emissions from the power plants that produce that electricity. Besides carbon dioxide from combustion, the other GHGs that healthcare buildings emit include methane (mostly in the form of leakage from natural gas piping); nitrous oxide (an anesthesia gas); and fluorinated gases used as refrigerants in coolers, freezers, and air conditioning systems.
GHGs trap heat in the atmosphere. Adding GHGs to the atmosphere increases the heat being trapped, causing climate change. If the healthcare sector were its own country, it would be the world’s fifth largest emitter of greenhouse gases.
The health impacts of climate change grow more obvious daily and include:
- increased allergy seasons
- changing disease vectors
- heightened food and waterborne disease
- rising mental health and stress disorders
- health impacts of increasingly severe weather events caused by climate change, especially the reduced ability of the healthcare system to deliver effective services in their wake.
While the Earth Day pledge is voluntary, many other jurisdictions are enacting regulations to reduce GHG emissions. In California, for example, more than 50 jurisdictions have passed laws forbidding the construction of new buildings (including hospitals) with natural gas connections. Other states require increasingly stringent energy codes. Through these efforts, these jurisdictions are pushing facilities to reduce the GHG emissions associated with on-site combustion and the consumption of electricity that’s derived from utility power plants that use combustion to generate electricity.
Some jurisdictions reward buildings with lower emissions through tax abatement or increased floor area allowances or expedited permitting. Some penalize those with higher emissions through fines or public disclosure and building energy rating grades, similar to health department restaurant ratings.
In January 2022, the states of Washington and Colorado, along with 31 municipalities, formed the White House Building Performance Coalition. The goal is to implement energy consumption and GHG emissions performance standards in their jurisdictions. These standards under consideration may replace traditional building energy codes that have typically used prescriptive design features and construction inspection to deliver predictable energy consumption. Additionally, they will apply to existing buildings, not just newly constructed or renovated ones.
What matters is the building’s actual energy consumption, and resultant source emissions, not how the building was predicted to operate. This paradigm shift may alter the expectations between owner/operators and the teams that design and construct their buildings. When a building’s actual energy consumption exceeds that predicted by the building design and construction teams, owners may well seek relief from those parties.
The process of reducing carbon dioxide emissions (and other GHGs) has come to be called “decarbonization.” So, what can be done to decarbonize hospital operation and construction?
Decarbonization in healthcare design
One of the most obvious tools for decarbonization in healthcare is through energy conservation and efficiency— reducing operational energy use from fossil fuel-derived sources will reduce carbon dioxide emissions.
Many of these measures are well known; they simply must be applied with greater rigor and breadth. For example, they include:
- well insulated and constructed building envelopes, particularly the reduction of glass as a wall material
- integration of high-efficiency lighting
- improved control of HVAC systems by reducing airflow during low-occupancy/off hours
Another decarbonization strategy is using on-site renewable energy systems to reduce the amount of fossil fuel-generated energy from utilities; however, very few healthcare buildings have enough space to produce all their energy on-site. These renewable energy systems can produce electricity through photovoltaic panels, and solar thermal collectors can produce hot water for both heating and domestic use.
Meanwhile, because the internal heat-generating loads in a hospital (lights, equipment, and people) operate more-or-less around the clock, most spaces in a hospital require air-conditioning year-round.
So, paradoxically, the air-conditioning and heating systems operate simultaneously. In most hospitals, a chilled water system provides cooling. The chilled water removes heat from the air via air handlers, circulates water back to the chillers, and expels heat from the system through cooling towers.
One way to reduce the use of natural gas is to recover heat from the cooling towers, and route it back to the heating system. This can be done through a special kind of “heat recovery” chiller or through water-to-water heat pumps. The systems use electricity to move this energy from the cooling tower system to the heating system. The cooling tower rejected heat is not exactly in time sync with the heat required by the heating system, requiring heat storage (usually in a water storage tank).
Push toward renewable energy
Another decarbonization pathway exists through reducing the carbon emissions associated with electric utility plant operation. This means moving away from the use of fossil fuel to generate electricity. This can include utility-scale renewable energy, such as wind or solar electricity, replacing the fossil fuel power plants. As the cost of these renewable energy systems is reaching parity with fossil fuel technology, many utilities are reducing the amount of carbon dioxide emissions associated with electricity generation.
In fact, many states have enacted renewable portfolio standards, requiring the utilities under their jurisdictions to progressively increase the amount of renewable energy electricity that they generate each year, thus reducing their carbon dioxide emissions.
Many hurdles still exist in this journey to a purely clean energy grid, mostly through the application of energy storage systems to smooth out the problems with the interruptability of solar and wind systems. However, healthcare systems can speed this journey along by advocating for more renewable energy generation from the utility that serves their facilities.
Because the utility grid GHG emissions are declining (many regional grids are getting “cleaner”), this leads to another decarbonization strategy that’s quickly gaining momentum: beneficial electrification. This strategy is focused on switching heating systems (both domestic water and space heating) from fossil-fuel (such as burning natural gas in a boiler or furnace) to electricity from a low carbon emission electric utility source. It’s important for each project to be evaluated not only on the energy used at the building, but the source energy consumed at the power plants serving that building.
One example of beneficial electrification at hospitals is the use of heat pump technology instead of fossil fuels. Roughly half the site energy consumed by a typical North American hospital comes from burning natural gas primarily to provide reheat to maintain space temperatures. Combustion energy also preheats fresh air, humidifies, sterilizes, and cooks.
Effects of electrification
Healthcare building electrical systems will obviously be affected by a shift toward electrification of various systems. At its simplest level, eliminating emissions from burning fossil fuels will require providing more energy from electrical sources, and ultimately from non-emitting electrical sources. So, all elements of building electrical systems will need to grow.
The magnitude and velocity of this change will be difficult to anticipate, as we have little experience with, for instance, all-electric kitchens in healthcare facilities. Nevertheless, building owners and designers must be moving aggressively to all-electric buildings now.
A recent report from the National Fire Protection Association Research Foundation found that at least some components of healthcare electrical systems, using antiquated demand factors, result in oversized electrical systems.
These impacts grow at higher levels of systems, with new emergency generators often being sized at three to four times the actual load they will serve. These problems will only magnify with the addition of yet more load to these systems, with obvious implications for space and cost that designers must now consider.
Another electrification trend likely to impact healthcare electrical systems is the burgeoning number of electric vehicles. The Economist Intelligence Unit estimates that the number of EVs will increase 51 percent in 2022, limited only by supply chain challenges.
The U.S. government announced a non-binding goal in August 2021 to make EVs account for one- half of new vehicle sales by 2030. The recently passed Infrastructure Investment and Jobs Act puts incentives behind that goal.
As electrification takes hold, demand for spaces with chargers, for both staff, patients, and fleet vehicles, will grow. Increased demand on healthcare electrical systems will be significant. This will require even greater expansion of healthcare electrical systems.
Basics of embodied carbon
While much of what this column has discussed is tied to operational carbon that’s emitted over the life of a building after construction, embodied carbon emissions occur during manufacturing and construction prior to building occupancy.
Indeed, as operational carbon emissions decline due to ongoing energy-efficiency improvements, embodied carbon’s relative share will grow to almost 75 percent of global construction-related emissions over the next 10 years, according to data compiled by Architecture 2030. Thus, it will be difficult to hit 2030 carbon emission reduction targets without addressing embodied carbon.
“Embodied carbon” refers to the sum of all greenhouse gas emissions during a product’s lifecycle. This involves mining, harvesting, processing, and manufacturing, as well as transporting, installing, maintaining, and disposing of them. It includes emissions of all greenhouse gasses, many of which have a larger warming effect than carbon dioxide, despite being emitted in smaller quantities.
Reusing and retrofitting existing buildings typically generates 50 percent to 75 percent less embodied carbon emissions than new construction. For new construction, most embodied carbon resides in the structural systems of a building. The second largest percentage occurs in the façade.
Focusing on low-carbon alternatives for just three materials—concrete, steel, and aluminum, which generate 23 percent of total global emissions (most from the built environment)—yields the most results. Alternatives includes supplementary cementitious materials such as fly ash, slag, and ground post-consumer glass; blended cements; mass timber; or simply using less concrete.
Rethinking MEP, refrigerant choices
After foundations, structure, and exterior cladding, MEP systems contribute the next most significant amount of embodied carbon in a building project. The industry is still trying to determine the role that MEP systems will play in efforts towards reducing embodied carbon. Quantifying the amount of embodied carbon in MEP systems is challenging due to the number of different materials and the extensive supply chain that goes into any given piece of equipment.
Also, most MEP systems tend to operate at a higher efficiency with more material. For example, many chillers operate at higher efficiencies with more copper in their tube bundles. Fans use less energy when ducts are larger and static pressure is lower, increasing the pounds of sheet metal used. So, while conventional wisdom is to generally reduce the amount of material used and to find alternative materials with lower embodied carbon, these may not be the best approach to reductions for MEP systems
