cove.tool helps optimize design strategies for net-zero energy and net-zero carbon buildings by making it easy with automation.

What is Net-Zero Energy (NZE)?

Net-Zero Energy refers to the ability of a building to offset the amount of energy required to build and operate throughout its lifetime. A building can be designed toward net-zero and offset its energy use in three ways.

  1. producing energy onsite via equipment like solar panels or wind turbines
  2. accounting for its energy use through clean energy production offsite
  3. reducing the amount of energy required through design optimization

These are typically complementary strategies with the first option directly linked to the initial costs of the building design. Achieving NZE is not technically dependent on the building being efficient, but the most effective strategy to achieve NZE is reducing the energy load. Optimizing the energy requirements of a properly designed building will exponentially help reduce power demand and the amount of power to produce or offset. Designing with cove.tool can provide a clear prediction of the current solution is moving toward net-zero by using its optimization engine to determine cost v. energy options. The simplified formula for achieving NZE is below.

Net-Zero Energy = Total Energy Used – Total Energy Produced

What is Net-Zero Carbon (NZC)?

Net-Zero Carbon refers to the ability of a building to offset the amount of embodied carbon from the process of creating a building. As described in our article on Embodied Carbon (kgCO2e), embodied carbon refers to the Greenhouse Gases (GHGs) emitted during the extraction, manufacture, transportation, construction, replacement, and deconstruction of building materials, together with the end of life emissions. Buildings will always use a high amount of embodied carbon and currently account for 40% of the world's carbon emissions, making carbon neutrality a top priority for architectural projects. Here are the main stages of carbon emissions for a building and who is most or least responsible for each one as published by the WorldGBC.

Achieving NZC requires the reduction and offsetting of non-sustainable building materials and construction practices that cause high carbon emissions, like specifying building materials with low kgCO2e values. Similar to achieving NZE, the reduction of carbon has an exponential effect on a building design that is net-zero carbon.

Net-Zero Carbon = Total Carbon Emitted - Total Carbon Avoided

Certification Requirements

There are now multiple certifications available for recognizing NZE and NZC buildings. Carbon neutrality is the key initiative for climate change survival of cities as outlined by Architecture 2030, who has established a goal to achieve a carbon-neutral built environment by 2040. Certifications help incentivize this goal. cove.tool can identify some of the design requirements early in the design process to help predict if a building is on track to be net-zero and to help users optimize towards it. Multiple organizations offer certifications for NZE and NZC buildings. Requirements for each certification differ slightly. Below is a breakdown of the different certifications available and how cove.tool features support each one.

Not every building will apply for certification, but design strategies toward net-zero buildings are simply good design. The lower the energy demand upfront, the less energy needed to make up later. This energy/carbon in = energy/carbon out is the neutral balance and net-result of zero energy/carbon wasted for net-zero strategies. Good design strategies working toward net-zero are beneficial to the architecture even without certification and is possible without high-priced products. cove.tool provides predictive tools to automate the insight of design decisions to provide users with an understanding of how to design for better building performance.

Users can leverage cove.tool features:

Design Strategies

Reduction is the over-arching design approach for all net-zero strategies as it directly affects the energy/carbon required to offset later. Reducing the energy demand on a building provides the appropriately sized system for building operations and can lead to large cost savings. Reducing embodied carbon through material decisions often results in enhanced occupant experience by decreasing harmful off-gassing from chemicals that affect occupants' productivity.

Its important to note that rule-of-thumb concepts are not enough to make a net-zero building as each building and its conditions are unique and optimization is the key to striking the neutral-balance. However, common strategies of approaching design help design teams understand the impact of their decisions. Applying any number of the below strategies during your design process will guide your work toward energy and embodied carbon reduction and keep your project on track toward net-zero.

Passive Strategies

Designing with passive strategies is about understanding the environmental constraints of the site and designing a response that does not require active mechanical systems. Examples include using ambient energy sources to cool, heat, shade, or ventilate a building space. Working with the natural conditions without requiring added electrical load helps decrease the energy required to offset for a net-zero building. Environmental qualities have a critical role in design to know what is specifically needed to minimize heat transfer through the building envelope (exterior walls), which will then rely less on mechanical systems to maintain occupant comfort levels.

The challenge with designing for passive strategies is that they must be incorporated in the early stages of the process to be effective. cove.tool provides an automated report for your project's site offering highly technical environmental analysis through simplified and action-oriented design recommendations specific to each project. cove.tool generates 6 Climate Passive Strategy Diagrams: Temperature & Humidity, Radiation by Sky Segment, Adaptive Comfort, Radiation Benefit, Psychrometric Chart, and Monthly Wind Rose. More details on using passive strategies are provided here.

Solar Shading

A specific passive strategy to highlight is the solar shading of your building. Formal qualities have a large role in the energy demand for every building and directly impact everything associated with the function and aesthetic desired during the design phases. A good way to think about this is to consider that the heat added to the inside of your building has to be adjusted to stay at set temperature levels, typically by an HVAC system. The less the mechanical system has to work, the less energy you need to use, and the more likely your design will reach net-zero. Solar shading encompasses a large scope of design strategies.

  • Building Massing
  • Orientation
  • WWR (Window to Wall Ratio)
  • Glazing Placement
  • Envelope Properties
  • Fenestration Performance
  • Traditional Shading Elements (fins and overhangs, light shelves, shadow boxes, and cantilevers)
  • Modern Shading Elements (frit, interior shades, dynamic glass).

cove.tool helps provide immediate results through full-floor plate analysis and rapid prototyping facade feature to understand better the design that is allowing more light in and how to shade it. Ultimately, cove.tool simulates the window properties of Solar Heat Gain Coefficient (SHGC) and Visible Transparency (VT) that simulate the energy demand added by the glazing design. Reducing the SHGC value while allows finding acceptable visibility for occupants will help keep the heat out, lowering demand on the mechanical system.

Active Strategies

A building's energy use refers to the energy required to operate and sustain the project once it's occupied. The metric is expressed as the energy per square foot per year (kBtu/ft2/yr) or as it is more commonly known as the EUI or energy use intensity. Using the cove.tool EUI chart will provide immediate feedback on the performance impact of the current building design.

Getting the EUI chart to zero represents a net-zero building.

EUI breakdown includes heating, cooling, lighting, equipment, fans, pumps, and hot water that represents the mechanical system of a functional building. A more detailed overview of what is covered in these categories can be found here. The goal is to increase the efficiency of the active system to decrease the demand for energy overall. There are many ways to achieve this and is precisely why cove.tool exists to help automate the simulation and optimization of these systems.

Showing a reduction of energy use is helpful, but to reach net-zero energy the optimal overall solution is crucial as every project has many variables and entities involved that don't all have net-zero as the top priority. Optimizing for energy reduction and initial cost helps the whole team quickly reach an informed decision on the best route forward with the best performing options at the table. Optimization is the core powerhouse of reaching net-zero building design. cove.tool has developed an accurate and powerful optimization engine to help bridge the gap between design intent and optimal design solution.

Renewable Energy

On-site renewable energy is another essential tool for reaching net-zero. Off-site renewable energy is essential as well but requires live operational data from the source energy (power plant) and is thus outside the scope of building design. Providing energy generation is the final tool for net-zero energy design and is possible through technologies that produce electricity, like wind or photovoltaic "solar" panels. The strategy is simple. Use natural energy sources like the wind or the sun to generate electricity.

For a building to reach net-zero, this strategy must produce enough electricity as what it uses annually. cove.tool provides a predictive input for PV loads with its energy analysis. By calculating the total square feet of panels and the type of panels used, cove.tool can provide the potential power generation for your building. The placement is assumed on the roof, the best location for facing the sun in most cases. Power generation is the final piece of building design to reach both net-zero-energy and net-zero-carbon status.

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