Systems Architecture for Zero Net Energy Performance in Multifamily and Office Buildings, Part 1
Systems Architecture for Zero Net Energy Performance in Multifamily and Office Buildings, Part 1 PHCPPros
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The Path to Zero Net Energy Buildings
This past decade has seen exponential growth in buildings registered to attain zero net energy (ZNE) performance. While there are many interpretations of “net zero,” the basic premise is that the building uses no more energy than it produces on-site in one year. To achieve this high standard, an engineer is well-served in adopting a proven architecture developed by integrated design teams worldwide and implemented in most ZNE buildings.
Architecture for Sustainable Development Goals
This architecture is ideal for office and multifamily buildings and is comprised of a high-performance building envelope; a high-mass, thermally conductive structure; ventilation separated from heating and cooling loads; and heat pumps with source process heat exchangers to move any heat source to any heat need to heat and cool the building efficiently.
Energy Use Intensity (EUI)
The prevalent metric for building energy use is Energy Use Intensity (EUI), measured as energy per square foot per year (kBtu/ft2) and varies by building type. According to the U.S. Department of Energy (DOE), the median source EUI for office and multifamily buildings are 116 and 118 kBtu/ft2, respectively. To achieve ZNE performance, this EUI must be reduced by more than 50%.
Successes in ZNE Buildings
Offices, dormitories, and barracks using the proven architecture described here have achieved EUIs as low as 25 kBtu/ft2. Multifamily structures have similar technical requirements and occupancies as barracks and dormitories and, therefore, should be included in these NZE successes. However, the lack of NZE multifamily buildings in the United States can be attributed to the lack of incentive by developers to make the necessary capital investments. Nonetheless, the technical requirements for these buildings are similar, emphasizing comfort, indoor environmental quality, and energy efficiency.
Reducing Greenhouse Gas Emissions
An additional benefit of this architecture is that the heat pumps used for heating, cooling, and hot water are all electrical appliances, with source process heat exchangers minimally reliant on fossil fuels. Most U.S. utilities power their electrical grid with fossil fuels, such as coal and natural gas. Therefore, simply converting to electrical appliances does not reduce a building’s greenhouse gas emissions. However, electric heat pumps in a central plant do reduce the number of smaller appliances in a building that use fossil fuels or create an opportunity for carbon offset through on-site power generation with solar photovoltaic arrays.
The Role of Integrated Design Teams
At this point, it should be apparent to an engineer that achieving NZE performance is more than specifying high-efficiency heat pumps and appliances. In fact, a common element in successful NZE building implementations is using an integrated design team. This team starts the process with a design charrette and includes all stakeholders, including the owner, the developer, the architect, the general contractor, mechanical-electrical-plumbing engineers, civil engineers, structural engineers, the landscape architect, the lighting designer, the certified energy manager, the controls contractor, and the contractors who will be responsible for implementing the design and operating the system. The traditional design-bid-build approach fails as a linear process with assumed roles and responsibilities, whereby an integrated design team collaborates throughout the development using a cross-functional systems approach based on established goals.
Building Envelope: Orientation for Passive Solar
While discussing the building envelope may appear mundane in the context of high-performance appliances, this is a critical first step often overlooked in new and retrofit construction. Without exception, the building orientation/envelope is the most critical factor in reducing energy consumption and improving occupant comfort.
Of the six factors affecting occupant comfort identified in ASHRAE 55, the four directly impacted by heating and cooling systems are air temperature, air speed, humidity, and mean radiant temperature. The building orientation and envelope most directly affect comfort and energy efficiency, considering the three means of heat transfer: convection, conduction, and radiation. A tight building envelope provides the engineer with direct control of air movement via convection, a function of forced-air heating or cooling and ventilation. A well-insulated building slows down heat loss or gain by reducing heat transfer via conduction through the walls, windows, and roof. The building orientation and shading directly affect solar heat gain by reducing the impact of short-wave radiation.
High Thermal Mass and TABS: Hydronic Heating and Cooling
To fully understand the performance of forced-air versus high-mass heating and cooling systems such as thermally active building structures (TABS), an engineer must comprehend the basic thermodynamic principles related to heat transfer and appliance efficiency. Heat
SDGs, Targets, and Indicators
1. Which SDGs are addressed or connected to the issues highlighted in the article?
- SDG 7: Affordable and Clean Energy
- SDG 9: Industry, Innovation, and Infrastructure
- SDG 11: Sustainable Cities and Communities
- SDG 13: Climate Action
The article discusses the need for buildings to achieve zero net energy (ZNE) performance, which aligns with SDG 7’s goal of ensuring access to affordable, reliable, sustainable, and modern energy for all. It also mentions the importance of integrated design teams and the use of proven architecture, which relates to SDG 9’s focus on promoting sustainable industrialization and fostering innovation. The article further emphasizes the role of building design in reducing energy consumption and improving occupant comfort, connecting to SDG 11’s aim of making cities and human settlements inclusive, safe, resilient, and sustainable. Lastly, the article touches on the reduction of greenhouse gas emissions through the use of electric heat pumps and on-site power generation, which aligns with SDG 13’s target of taking urgent action to combat climate change and its impacts.
2. What specific targets under those SDGs can be identified based on the article’s content?
- SDG 7.3: By 2030, double the global rate of improvement in energy efficiency
- SDG 9.4: By 2030, upgrade infrastructure and retrofit industries to make them sustainable
- SDG 11.6: By 2030, reduce the adverse per capita environmental impact of cities
- SDG 13.2: Integrate climate change measures into national policies, strategies, and planning
The article highlights the need to improve energy efficiency in buildings to achieve zero net energy performance, which relates to SDG 7.3. It also emphasizes the importance of retrofitting buildings and adopting sustainable design practices, aligning with SDG 9.4. The article further discusses the role of building design in reducing energy consumption and improving occupant comfort, connecting to SDG 11.6. Lastly, the article mentions the reduction of greenhouse gas emissions through the use of electric heat pumps and on-site power generation, which relates to SDG 13.2.
3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?
- Energy Use Intensity (EUI) measured as energy per square foot per year (kBtu/ft2)
- Reduction in EUI by more than 50% to achieve zero net energy performance
- Adoption of integrated design teams for building projects
- Increase in the use of high-performance building envelopes
- Shift of cooling loads from peak to off-peak hours through building design
- Improvement in heat pump efficiencies through source process heat exchangers
The article mentions Energy Use Intensity (EUI) as a metric for building energy use and highlights the need to reduce EUI by more than 50% to achieve zero net energy performance. This can be used as an indicator to measure progress towards SDG 7.3 and SDG 11.6. The article also emphasizes the importance of integrated design teams, high-performance building envelopes, and the shift of cooling loads to off-peak hours, which can be indicators of progress towards SDG 9.4 and SDG 11.6. Additionally, the improvement in heat pump efficiencies through source process heat exchangers can be an indicator of progress towards SDG 7.3.
4. Table: SDGs, Targets, and Indicators
| SDGs | Targets | Indicators |
|---|---|---|
| SDG 7: Affordable and Clean Energy | 7.3: By 2030, double the global rate of improvement in energy efficiency | – Energy Use Intensity (EUI) measured as energy per square foot per year (kBtu/ft2) – Reduction in EUI by more than 50% to achieve zero net energy performance – Improvement in heat pump efficiencies through source process heat exchangers |
| SDG 9: Industry, Innovation, and Infrastructure | 9.4: By 2030, upgrade infrastructure and retrofit industries to make them sustainable | – Adoption of integrated design teams for building projects – Increase in the use of high-performance building envelopes |
| SDG 11: Sustainable Cities and Communities | 11.6: By 2030, reduce the adverse per capita environmental impact of cities | – Adoption of integrated design teams for building projects – Increase in the use of high-performance building envelopes – Shift of cooling loads from peak to off-peak hours through building design |
| SDG 13: Climate Action | 13.2: Integrate climate change measures into national policies, strategies, and planning | – Reduction in greenhouse gas emissions through the use of electric heat pumps and on-site power generation |
Behold! This splendid article springs forth from the wellspring of knowledge, shaped by a wondrous proprietary AI technology that delved into a vast ocean of data, illuminating the path towards the Sustainable Development Goals. Remember that all rights are reserved by SDG Investors LLC, empowering us to champion progress together.
Source: phcppros.com
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