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Net-zero energy buildings
29 December 2021
Manoj Singh

How Can Commercial Buildings Move Towards Net Zero Goals?

It’s inevitable. Amid the chaos of rising energy prices, climate change and depleting energy resources, solutions must be explored. In a world where building construction consumes the lion’s share of energy, the use of building energy becomes a primary target for change, innovation and improvement. Along with all other types of buildings, commercial buildings too must contribute to the construction industry’s move to inch closer to net zero goals. Guiding this move, accurate and reliable MEP design and mechanical design services can make the journey easier.

Commercial buildings have been shown to be major energy consumption culprits. Although they come in different forms, some with unique energy needs, it is space heating that uses 25% of the total energy consumed in commercial buildings.

Energy-efficient strategies can be exercised during the design and construction of new buildings and while renovating existing buildings. Reducing the dependence on energy derived from fossil fuels may require using on-site and off-site energy sources. However, we will concentrate on on-site solutions.

Commercial buildings traditionally use electricity and natural gas for their energy needs, with most buildings having individual heating and cooling systems. Central heating and a cooling plant to distribute steam, hot water or chilled water to multiple buildings is used when many buildings are situated close together.

To reduce environmental impact, commercial buildings are moving to net zero energy goals. Net zero is a term that is frequently bandied about, but what do we really mean?

Conceptually, a net zero building produces as much energy as it uses in a year. At the moment, very few buildings can make that claim, but technological advances, renewable energy systems and inspired research is making it a more common reality. These buildings reduce operational costs and carbon footprints.

Net zero energy buildings have:

  • Intelligent building design to reduce energy needs
  • Renewable energy systems to power these new needs

Broadly speaking, four different components of net zero energy can be thought of as:

  • Net Zero Site Energy
  • Net Zero Source Energy
  • Net Zero Energy Costs
  • Net Zero Energy Emissions
Site Energy

It is the energy used and generated at a building. For a net zero site energy building, all building energy used over a year must be generated at the site.

Source Energy

This is the initial energy needed to take and deliver energy to a site, including energy lost during generation, transmission or distribution.

Energy Costs

This may be the easiest parameter to measure. A building with net zero energy costs has a utility bill of $0 in a year.

Energy Emissions

For net zero energy emissions, a building either uses no energy that results in emissions or produces emissions but exports emissions-free energy (usually from on-site renewable energy systems).

Grid Connection & Net Zero

It is quite likely that net zero energy buildings are also connected to the electric grid, so that electricity produced from natural gas, electric and other sources can be used when the renewable energy generated falls short of the building’s energy load. More interestingly, when excess on-site energy is generated, the extra energy can be exported back to the grid.

Commercial buildings can move towards net zero energy goals by ensuring energy-efficient design. Some of the options that design teams have are as follows:

  • Design teams use energy analysis tools to create efficient designs.
  • Using high-performance HVAC systems can increase energy efficiency.
  • Design strategies can focus on reducing energy loads with high-performance building envelopes, air barrier systems, daylighting, sun control and shading devices, astute selection of windows and glazing, passive solar heating, natural ventilation and water conservation.
  • Reduced building energy loads can be supported by energy-efficient lighting, electric lighting controls, high-performance HVAC and geothermal heat pumps.
  • Combined heat and power systems, fuel cells and microturbines may not generate renewable energy, but they convert fossil fuel energy into heat and electricity for energy efficiency.
  • Using low-cost, locally available, renewable sources contribute less overall greenhouse gases to the atmosphere.

So, how is renewable energy generated?

  • Photovoltaics (PV), solar water heating and wind turbines can generate energy on site.
  • Biomass can generate renewable on-site thermal energy by burning wood, wood pellets, agricultural waste and other products to heat spaces and service water heating.
  • Biofuels, such as biodiesel, can be used with traditional fossil fuels to cater to thermal loads.
  • Wind energy uses wind turbines to generate mechanical power to run electric generators and produce the energy.

Governments are encouraging the move towards net zero goals too. The Net Zero Energy Commercial Building Initiative (CBI) is looking to build net zero energy buildings by 2025 using numerous public and private partnerships. The following buildings seem to have got it right:

  • A 220,000 sq. ft. building project in America achieved net zero site energy using a performance-based design process. The project used advanced heat recovery technologies, photovoltaic power, daylighting, natural ventilation and an energy-efficient data centre.
  • A maximum energy efficiency project in the US involves classrooms, office spaces, an auditorium, a resource center and a wastewater-purification system in a greenhouse. The building generates on-site electricity through a roof-mounted PV system over the building and over the parking lot. Interconnected with the city grid, any excess electricity generated by the solar panels is exported to the city.
  • A US courthouse was renovated by installing a geothermal heating and cooling system and a solar panel array. The systems generate enough energy to meet the building’s electricity requirements. Excess energy generated is sent to the local energy grid. The building also has lighting fixtures that respond and adjust to natural lighting intensities as well as storm windows with solar films to reduce heating and cooling loads.

The concept of intelligent building design would be incomplete without including smart buildings. These buildings use:

  • Smart water meters
  • Smart system to operate their lights, turning them on. off or dimming them remotely, using a mobile app
  • An uninterruptible power source (UPS) system that provides backup power for modems during outages

Companies in commercial buildings can monitor their building services remotely and send alerts when a battery is running low.

Now, how can commercial buildings make these changes?

Suitable simulation software can help the process of energy modelling and simulation, which can help calculate energy consumption quantities. This software can analyse the building’s energy model and determine the suitable energy-efficiency design strategies to use, such as passive design strategies, efficient HVAC systems and renewable energy systems.

Energy Modelling & Simulation
  • Autodesk’s Revit software can be utilised to create a virtual model of a building to understand energy-saving potential and sustainable design options.
  • The software helps introduce retrofit approaches, such as control of internal loads, devising operating schedules, planning lighting and improving the building envelope.
  • Interior lighting needs and occupancy schedules can be considered.
  • Sensors can be placed in the model to minimise lighting for empty rooms.
HVAC Systems
  • HVAC systems can include biomass heating to be more cost-effective and environment-friendly.
  • Incorporating a wireless temperature monitoring system to a HVAC system will adjust the temperature with reference to occupancy and activities.
Building Facades
  • Building facades for hot climates can use passive cooling, shaded walls, glazing that reflects sunlight, light exterior colors, insulation and double glazing.
  • In cold climates, passive solar heating, daylighting, insulation or double glazing can be used.
  • Double roofing eliminates or minimises build-up of heat between the structure and the roof, reducing inside temperature.
  • Green roofs retain water, improve air quality and green space, reducing energy consumption.

Thus, a gamut of MEP engineering design considerations for commercial buildings can be planned, calculated and visualised with energy modelling and simulation. These considerations can include material selection, building envelope improvements, HVAC and lighting systems, occupancy loads and the incorporation of renewable energy sources. With the right HVAC design services and mechanical engineering design services support, commercial buildings can move confidently towards net zero goals.

XS CAD has valuable experience providing mechanical design services for design consultants. Our range of services for building design firms across the world include mechanical engineering design services, HVAC design services and other MEP design services, and we offer retained teams when required. We create these, designs, models, and drawings by using Revit, AutoCAD, Navisworks and BIM collaborate pro for cloud collaboration.