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Zero-Carbon Heat for Buildings—How is it Possible?

How will we heat our buildings when we no longer use fossil fuels? It’s a really big and urgent question that is rarely discussed.

Last week I had to address the problem for Island Health, whose facilities managers are working hard to reduce the carbon footprint of their hospitals and other buildings on Vancouver Island, here in British Columbia.

How do you heat a hospital, if you are not using oil or natural gas?

Gas is an easy way to heat a building, and a lot better than coal, which is how hospitals used to be heated. Oil is easy too—but they are all fossil fuels, and as such they are the primary cause of global warming, which is going to cause chaos, misery and death for millions unless we can phase them out—and rapidly.

Island Health has responsibility for all public healthcare facilities on the Island, and for their efforts on the energy front their Energy Efficiency and Conservation Team won a B.C. Hydro Power Smart Leader Award in 2012 and the Energy and Environmental Stewardship Award from the Canadian College of Health Leaders in 2013. Back in 2007, they set a goal to reduce their greenhouse gas emissions from 28,000 to 18,000 tonnes by 2020, which they have been hard at work at ever since. www.viha.ca/about_viha/environment.htm

Many measures can improve a hospital’s efficiency and reduce its heat-load, most of which Island Health is doing. These include more efficient lighting; energy optimization systems such as presence detection, luminance level optimization, time schedule based controls and demand controlled ventilation; high-efficiency chillers, boilers and water heaters; heat exchangers; more efficient pumps; and the integration of subsystems to achieve whole-building performance. According to the US National Renewable Energy Laboratory, up to 50% of the energy can be saved by these and other means. www.nrel.gov/docs/fy10osti/47867.pdf

The next step is to take out gas altogether, and substitute it—but with what? Island Health is not alone in facing this challenge: in the European Union hospitals that have embraced the Renewable Energy Systems Hospitals Challenge are exploring options to achieve zero carbon hospitals, and developing plans for 50% of their energy to come from renewables by 2020. www.res-hospitals.eu

So let’s get down to it. There are three choices when it comes to renewable heat:

  1. Heat from burning biomass
  2. Heat from air-source, ground-source or water-source heat-pumps
  3. Solar thermal heat with inter-seasonal storage

The Biomass Option

The biomass option seems easy, since the engineering is straightforward, and biomass is widely considered to be carbon-neutral on the basis that a cut forest will regenerate, restoring the carbon lost in cutting. As a fuel, however, kilo for kilo, it releases more CO2 than coal, so the entire strength of the argument depends on what happens in the forest, or wherever the biomass is obtained from.

If the biomass comes from forests wastes that would otherwise rot or be burnt in a slash pile, then the carbon numbers look good, as long as the biomass is within 100 kilometers of the biomass furnace.

 

If it comes direct from the forest, however, hospital facilities managers will need solid evidence of really good forest management practices, based on the best silviculture techniques, to justify the claim that the forest really is re-growing its store of carbon.

If it takes eighty years to re-accumulate the carbon, that’s not much use on a planet where we are counting the years before the climate disaster becomes unstoppable on the fingers of two hands. If the forest carbon is not being restored, burning biomass is worse than burning coal. http://thetyee.ca/News/2014/04/23/Biomass-Fuel-Is-It-Worse-than-Coal/

Biomass is certainly popular, and in places such as the Lillooet Rec Centre where it is being fueled with forests wastes it certainly makes sense. There are hospitals in Italy, Spain, Scotland and England that are already using biomass, or planning to do so. Given the paucity of forests in Europe, however, and the popularity of shipping wood pellets from Canadian forests, I have serious questions as to whether the biomass they plan to use is actually carbon neutral.

There is one other form of biomass - garbage. Incineration is a hot topic, generating strongly held feelings, but I do need to report that in Copenhagen, the National Hospital will be heated by hot water and steam piped in from new Amager Bakke waste incineration plant. And since the plant is being designed by the highly creative Bjarke Ingels Group (BIG), it will also have a ski slope and a climbing wall. Those Danes - they understand that it if’s not fun, it’s not sustainable.  www.earth911.com/tech/research/amager-bakke-power-plant

So what’s the second zero-carbon option?

The Heat Pump Option

Three of the large buildings at Brentwood College in Mill Bay are being heated with water from the Saanich Inlet, using heat pumps to do their magic. It might seem counter-intuitive, since the water is positively bone-chilling, but in the hands of a good heat-pump it’s got plenty of heat. www.grundfos.com/about-us/news-and-press/news/brentwood-college-school-a-study-in-sustainability.html#an_ambitious_experiment

In Poland, the hospitals at Myslenice and Wadowice are getting their heat from geothermal heat pumps; at the Sucha Beskidzka hospital they actually rejected the use of biomass in favour of geothermal, using a radial drilling method which has yet to arrive in North America. http://geothermic.tracto-technik.com

In Hungary, the Zala County Hospital has a geothermal heating system with boreholes two kilometers deep; this saves them nearly 2,000 tonnes of CO2 a year at €750/tonne, or €37/tonne when spread over 20 years. In Germany, the Ethianum Hospital in Heidelberg uses 45 ground-source heat boreholes, some up to 70 meters deep.

At the Akershus University Hospital, in Norway, ground-source heat pumps supply 85% of the heat and 40% of the total energy. At Norway’s Stokmarknes Hospital, thermal energy from the sea provides nearly 90% of their heat-load. The latest European insulated pipes can transfer the heat at 200°C for over 20 kilometres with hardly any loss of heat, so in principle any large building within 20 kilometres of the ocean could be heated by this means.

An advantage of geothermal heating is that it provides year-round heat, since the temperature is stable below ground even when it’s minus 20 in the deep of winter; it can also be used for air-conditioning in the summer, replacing the heat extracted in winter. The main reason we don’t see more of it in British Columbia is that it’s expensive, and natural gas is very cheap compared to Germany and Poland, where they pay almost four times as much ($11 per Mmbtu, compared to $3 in Canada). They also have to be constantly nice to Russia, to be sure of a steady supply.

Solar Thermal Heat

The third option for zero-carbon heat is solar heat direct from the sun, with a summer surplus being stored underground for use in winter. This has been happening on 52 homes in the Drake Landing subdivision in Okotoks, Alberta, just south of Calgary, since 2007. 700 solar hot water panels on the garage roofs generate more heat than needed in summer, which is pumped into an underground storage area where there is no groundwater intrusion and brought back in winter, meeting more than 90% of their space heating needs. www.dlsc.ca

Inter-seasonal heat transfer is being taken very seriously in Europe, where it is seen as being more cost-effective and requiring less space than biomass, since the heat-storage area can be installed under a car park.

In Okotoks, the heat is brought back directly, but in China’s Himin Solar Valley in Dezhou, an hour south of Beijing (www.chinasolarvalley.net) and in Europe, especially Denmark, which has 35 solar thermal plants larger than 350 kWth, communities are combining large-scale solar thermal arrays and seasonal storage with ground-source heat-pumps, achieving a CoP (coefficient of performance) of 8.5, compared to the normal 3-5 to 4.0. This means that for every unit of energy needed to run the heat pumps, 8.5 units of stored solar energy are retrieved.

Compared to burning coal, oil or gas, which involves many heat losses and an overall system energy efficiency of only 56-75%, the direct gathering of solar heat combined with a heat-pump has 99% energy efficiency—and solar thermal collector prices have fallen four-fold in Europe since 1995. www.sunmark.com

The Zero-Carbon Conclusion

In Europe, the Solar Thermal Industry Federation sees a future in which 50% of all space heating is provided by stored solar heat by 2030, and 100% solar heated buildings become the norm. For building renovations, they see 50% of the heat being provided by stored solar thermal heat.  www.estif.org and http://www.estif.org/statistics/st_markets_in_europe_2012

And it is cloudy grey Denmark that is leading the charge, proving that solar thermal does not need long sunny winter days to make it work.

Back here on Vancouver Island, two new hospitals are being built in the Comox Valley and Campbell River. They are being built to achieve LEED Gold certification, which is great, but LEED has always been soft on greenhouse gas emissions, and the current plans call for the hospitals to be heated with natural gas, which is a huge disappointment. When we could have had North America’s first major buildings heated by zero-carbon ocean heat or stored solar heat with ground-source heat pumps, they are going with gas, releasing many thousand tonnes of carbon dioxide to the atmosphere every year.

Why? Fundamentally, I’m guessing, because of the money. The hospitals are being built through a P3 public-private partnership, and someone decided that they should not spend the extra money needed to eliminate their greenhouse gas emissions. The Design Principles call for the team to consider using alternative sources of energy, and to explore opportunities for using waste heat or biomass. Considered, it would appear, and rejected in favour of natural gas. http://nihp.viha.ca/about/design-principles/

If we are to achieve the necessary phase-out of fossil fuels, it will have to to be driven by regulation. In Britain, all new residential buildings must be zero carbon starting in 2016; and all new buildings by 2019. In California, all new residential buildings must be zero-net energy by 2020; all commercial buildings by 2030. So they have shown what is possible.

Here in British Columbia, where we have many LEED qualified architects and engineers, we should be following suit. We could have had two world-class zero-carbon hospitals. Instead, they will burn more natural gas.

 

 

For my full presentation to Island Health, see http://www.slideshare.net/GuyDauncey/here-comes-the-sun-strategies-to-achieve-lowcarbon-and-zerocarbon-health-facilities-guy-dauncey-may-2014