The environmental protection aspect deals with climate change issues, resource depletion, land use and ecology, and waste concerns and impact of cities. The human social concerns and issues deal with justice, intragenerational equity, intergenerational equity, and health and well-being issues. On the other hand, the economic development deals with developed and developing counties, employment, modernization, and technological changes.
To solve current issues toward sustainable designs, designers should meet most of the items listed under each of the three pillars.
Spreading knowledge and engagement are ultimately the top most factors to help in reducing energy consumption, pollution and emission, and other issues such as global warming. The process starts with engagement and knowledge spreading, but it should be a closed cycle and thus needs feedback on performance. There has to be supplies that provide low and zero carbon energy and, lastly, investment. With no commitment from big industrial countries, no progress would be achieved.
There are many organizations who started net-zero marketing and application such as environmental organizations, research centers, universities and schools, and some engineering solutions which aimed to save costs and energy. In the United States, California and New York are leading the way to net-zero designs. Although they occupy more than 20% of the total population in the United States, they contribute to less than 10% of the total pollution emissions.
Following design standards is the first step in the design to achieve a net-zero energy building as it is important to define the sources and inputs that would be necessary to quantify the outputs and check what it needs to balance the net-energy consumed. The next step is to simulate the energy consumption using various energy modeling techniques and tools to optimize the following:
All factors should be considered together by employing passive heating or cooling strategies, such as solar chimney and direct heat gain through south-facing glazing and/or isolated gain or sunspace, considering all possible exterior wall construction that avoids thermal bridging and increasing the R-value in all roof construction, using efficient lighting system, utilizing daylighting sensors and occupancy sensors, and lastly using energy-efficient office equipment for commercial buildings and energy-efficient utilities for residential houses and buildings.
The designer should then implement life cycle analysis, net-zero water system, and net-zero energy and optimize the design as per occupancy levels.
There are three principles to achieve a good net-zero energy building design:
Building envelope measures
Not only the building should be oriented to minimize HVAC loads, but shades and overhangs should be used to reduce the direct sunrays. Multiple options are available such as roof overhangs, shades and awning, and vegetation. To reduce the heat gain through windows, the designer should avoid glazing on the east/west façade. Other measures to reduce heat gains are to increase insulation on opaque surfaces, use glazing with low solar heat gain coefficient values, use double-skin façade, and refine the building envelope to suit location conditions.
Energy efficiency measures
The first utmost factor is selecting the right-size systems for the building. This can be achieved by following ASHRAE Standard 90.1 safety factors in the design, applying factors to reasonable baseline cases, and using simulation to model the design and predict the optimized requirements. In the simulation, part load performance should be considered which would come useful when using variable volume systems, variable speed drives, variable capacity boilers, variable capacity chiller systems, and variable capacity pumping systems as well. In addition to this, the designer should consider using high-efficiency lighting and control systems such as LED lights, high-performance ballasts, dual circuited task lighting, occupancy sensors, and daylighting dimming sensors.
The designer should shift electric loads during peak demand which would optimize the energy consumption. Some recommendations for optimizing the HVAC loads are (1) using heat recovery chillers, (2) using underfloor air distribution systems, (3) using high-efficiency chillers, (4) using passive cooling, (5) applying thermal storage using phase-change materials (PCMs), (6) using combined heating and power (CHP), and (7) using natural ventilation.
At the end of the construction phase, commissioning is a crucial step to ensure the building is performing as the intended design and is meeting its objectives. Commissioning phase verifies that the building’s energy-related systems are installed and calibrated and perform according to the owner’s project requirements, basis of design, and construction documents. The commissioning phase should cover at least the HVAC systems and controls, lighting and daylighting controls, domestic hot water system and any renewable system such as wind and solar. Building commissioning can reduce energy use, lower operating costs, reduce contractor callbacks, and improve occupant productivity. Successful implementation of the commissioning process can yield 5–10% improvements in the energy efficiency.
Renewable energy measures
Go green! Maximizing the energy sources are done through the first two measures, the building envelope which promotes using less energy and the efficient utilities and equipment measures. The renewable energy measures are more expensive than these two measures, and for that designers should start with the first two measures and optimize their design which would reduce the energy requirement needed in this step.
There are various renewable energy resources, such as solar which can be used for generating electricity, storing energy, and heating water, wind, biomass systems, and other sources.
Solar water heating systems include roof-mounted solar collectors that heat a fluid which would be used to heat water stored in a cylinder. Two collector types are usually used: the flat plate and the evacuated tube type. Flat plate collectors are usually cheaper. The solar water collectors heat the water that would be stored in a cylinder directly or indirectly by heating another fluid that would heat the water. Photovoltaic systems can be used to store energy and help in shifting the peak load.
Wind systems provide energy a very effective cost if the wind is continuous and steady and its speed above 10 mph (4.47 m/s), but it is recommended to be above 25 mph (11.2 m/s).
Biomass systems could provide heat by burning the biomass material. Some examples include forests, urban tree pruning, farmed wastes, wood chips, or pellets. However, the burners usually require more frequent cleaning than oil and gas boilers.
Geothermal systems provide good source for both cooling and heating by running the refrigerant pipes under the ground that usually provide nearly constant temperatures. These systems do not produce emissions. Such systems can provide coefficient of performance of 3 or even higher.