This article outlines a two-tier design approach that can assist architects to achieve their goal of a Net Zero Energy building. The first stage is to reduce the overall operating energy demand of the building; and the second is to replace traditional energy derived from fossil fuels with energy from renewable sources. Recent technological advances are making renewable energy options more attractive, both in terms of output and cost recovery.
By Loghman Azar
Despite the technological advances, decreasing cost and a range of incentive programs for renewable energy, the most commonly used sources of energy in Canada are still fossil fuels and nuclear power, as both remain readily available and inexpensive.
Arguments in favour of nuclear power as a clean and renewable energy source overlook concerns about the safe disposal of radioactive waste, taking an ‘out of sight, out of mind’ approach to the long term implications of storage in deep geological repositories. Similarly, while research on CO2 capture and storage is ongoing, this is also a ‘tail pipe solution’ – one that endeavours to solve a problem that we now have the means to eliminate altogether.
Meantime, the impact of excess CO2 on climate change, including depletion of the ozone layer, polar ice melt, receding glaciers, warming of the oceans, and air pollution, among other problems , continue unabated. By contrast, renewable energy sources such as solar and wind are clean, with no harmful by-products – but they do require proper ‘technology’ and ‘design’.
Energy Use in Buildings
Of the total energy consumption in North America, approximately 45% is used in the construction and operation of buildings. Commercial buildings account for 20%, single family homes for another 20%, and multi-family residential buildings a further 5%: Ironically, more than 85% of Ontarians are living in multi-family buildings, and numbers are growing. The remaining energy consumption is related to industrial and agricultural use [25%], and transportation [30%].
Paying for Energy
As with other commodities, we have traditionally purchased electricity or natural gas from suppliers and distributors and paid for our usage at market rates on a monthly basis. A more recent option, and a growing trend, is to become an owner-producer of on-site energy, using what one needs and selling the excess power back to the grid. As the cost [particularly of photovoltaic technology] comes down and awareness rises, this option is becoming increasingly popular.
The challenge for architects is to integrate these new technologies in a way that maximizes their efficiency without compromising the other design goals for the project. This requires a two-tiered approach to design: the first step being to reduce the energy demand of the building to the greatest extent possible, and so reduce the amount of operating energy required; the second is to provide that energy from renewable sources in a way that is cost-effective and at the same time flexible enough to respond to future changes in the market.
Energy vivacity requires electricity to be used or lost, In the absence of grid takeback [reverse metering] storage technologies such as batteries, superconductors and flywheel may be used for storing energy. Some electric vehicles such as Tesla have developed highly advance battery packs, as well as batteries for homes.
A Holistic Approach to Net-Zero Energy
The primary imperatives in a holistic approach are: 1. to design for human comfort; 2. to create a healthy community; 3. to reach a balance between the made and the natural environment; 4. to switch to renewable energy production.
The majority of, if not all, existing buildings designed prior to the year 2000 are likely to be energy inefficient by today’s standards. However, by applying the two-tiered design approach, new buildings can be designed to be energy self-sufficient or even net-positive.
The purpose of the two-tiered approach is to help prioritize appropriate strategies. I refer to the first tier as NatureWISE solutions, which have their origins in the strategies of passive design; and the second tier as NatureRICH solutions, which draw upon the energy inherent in natural environmental systems, to meet the energy needs of the building.
As noted, the NatureWISE solutions are primarily aimed at minimizing the demand for energy and improving the passive design performance of the building. These include daylighting, natural ventilation, appropriate orientation, solar shading, airtightness, and super-insulation. In addition to these strategies, new technologies, or more efficient versions of existing technologies, can also contribute to reduced energy demand. These include compact massing or layout, high efficiency appliances, lighting, fans, automatic controls such as electricity current optimization daylight / occupant sensors, and heat recovery systems for ventilation, grey water and mechanical equipment.
As a point of reference, both the American Institute of Architects and its Canadian counterparts such as the Ontario Association of Architects have prepared energy Use Intensity (EUI) benchmarks for various building types. Different building types of course have different energy demands.
For example, supermarkets, laboratories or hospitals have a high operating energy demand, while schools are at the lower end of the spectrum. Based on these and other criteria, different energy use targets may be considered, such as the levels of energy consumptions defined by the 2030 Challenge, or the higher levels identified in BC’s Energy Step Code.
NatureRICH solutions are primarily for the purpose of generating power, and should be considered supplemental to the NatureWISE solutions outlined above. The effective application of NatureWISE solutions is a prerequisite for achieving higher levels of performance and reaching a net-zero or net-positive outcome.
It is important to understand the costs and benefits of each NatureWISE strategy under consideration, in order to determine at what point, and to what extent, NatureRICH renewable energy solutions should come into play. When supply and demand are equal, the choice remains, whether or not to generate more power than needed for self-use, and sell the excess energy back to the local or regional distribution grid for purchase by other users.
Off-site Power Generation
Renewable power can be generated using either off-site or onsite installations. For on-site application, the architecture of the building plays a significant role; however, the primary concern in off-site applications is on the productivity of the plant, and the size and efficiency of the distribution grid to which it is connected Off-site applications are usually found in remote locations.
They are large, and strategically placed to maximize production from the available wind, solar or other renewable sources of energy. Together, they make up a critical part of our current and future energy infrastructure. In dense urban areas, where it is more difficult to establish successful on-site applications, most buildings will continue to rely, at least in part, on the existing infrastructure and distribution system to deliver much of their renewable electricity.
However, these systems still rely on century-old technology which, as the massive east coast blackout of 2003 reminded us, can be very vulnerable. Although, with emerging digital tools, many aspects of the existing grid system may be enhanced by the integration of intelligent management, operation, and control systems.
In Ontario, consumers may already purchase electricity from power generation companies that harness energy from clean and renewable sources. However, at present that is only able to serve small segments of the market is sometimes limited by the transmission capacity of the existing grid. While solar and wind are the primary sources of renewable energy generation in remote locations, other viable options include geothermal power, hydropower, and biomass energy. All types of renewable energy generation can be effective at the community scale when circumstances permit. In Stockholm, for example, 100% of the city’s bio-waste is converted to energy, most of it in neighbourhood co-generation [heat and power] plants.
On-site Power Generation
Solar, wind and geothermal technologies are also suitable solutions for on-site applications, while micro-hydro may be considered for sites that are near rivers and streams. Power generation incorporated into the buildings themselves is largely solar-based, installed on the roofs. A growing solar industry offers not only stand-alone panels, but also Building Integrated Photovoltaic technology that can contribute to an aesthetically pleasing and elegant architecture. Small building-mounted wind solutions can also be considered on some sites.
Once again, the growth rate in the industry is accelerating. Investment is driven by good returns, and economic benefits such as job creation. Most crucially, this growth is based on a shared vision of a future free from the pollution that is an inevitable consequence of burning fossil fuels.
The optimal angle for the installation of solar arrays is based on the sun’s azimuth and angle of incidence at the given location. While this used to be critical for maximizing output, the new generation of photovoltaic panels are able to capture solar energy at different angles with reasonable efficiency. Installing a solar array on the roof of an existing building is often easier than a façade-mounted installation, as solar access can more easily be achieved. Large expanses of roof can represent a business opportunity, as building owners can potentially lease these roofs to a utility company, who would then install PV arrays on the roof at their own expense, selling the power, but paying an annual fee to the owner.
This approach is popular in Canada, perhaps because technical know-how and financing are often packaged together. However, an owner may choose to finance the installation, use the power themselves, and sell any excess to the local electric utility. Both these approaches apply equally to ground-based site installations, rarely practicable in densely built up areas, but much easier on larger suburban lots.
Energy Independence – Cost vs Value
Architects and building owners alike are interested in the functional performance of the building, as well as its overall appearance and form. An open dialogue on the efficiency measures and deploying energy generation technologies in buildings is more often welcome than not, but cost remains the primary deterrent to adopting them.
Most often in Canada, the discussion of photovoltaic energy leads immediately to a free-standing roof application as opposed to an application integrated into the building façade. The cost premium for building integrated photovoltaics, as well as the complicated process for obtaining necessary city permits are the main deterrents. A life cycle approach that takes into account the advantages of energy independence might come to a different conclusion.
Conclusion: Creating a Culture of Conservation
While conscientious design can result in significantly lower energy consumption in buildings, changing societal attitudes is equally important. A conscious change in lifestyle and a concerted effort to break our many wasteful habits will reduce the energy demand of our society as a whole.
By turning off lights and computers when not in use both at home and in the workplace, encouraging a balanced energy consumption model throughout the daily [or even seasonal] cycle of building operations; and by creating dense and diverse neighbourhoods, we can move toward a healthier and more affordable future.
This vision, underpinned by the two-tiered design approach described here, challenges the assertions of those who claim that strategies that are good for the environment are bad for the economy. In fact, NatureWISE and NatureRICH strategies make good business sense, and are known to result in buildings that perform better and cost less to maintain.