Net Zero Carbon Building Case Study

 

Global warming is happening, and 1.5 C is set to be the maximum temperature we should achieve by 2050. The cause of global warming is mainly greenhouse gas (GHG) emissions from fossil fuel-based production. Furthermore, the building and construction sector contributes 37% of energy and process-related carbon dioxide emissions (P. Un Environment et al., 2024)​. Therefore, initiatives emerged worldwide, namely the World Green Building Council (WGBC). They advocate a completely Zero-carbon building by 2050 (D. Satola et al., 2021)​.

Net-zero carbon building is a balance between renewable energy resources used by the building and the embodied carbon produced by it (L. E. T. Initiative). Still, some definitions also consider other factors, such as occupant and transportation carbon emissions, to be reduced by renewable resources and purchased carbon offsets​.

Net zero building has various definitions and frameworks across the countries. However, carbon emission reduction is the primary objective of the design. According to D. S. Finnegan (2024). The design process of net zero carbon building includes (1) understanding the operational energy used benchmark on each building type and location, (2) calculating the LCA and EPD of material, (3) Analysing the opportunity of the site to decide the strategy. For example, consider the orientation, vegetation, and potential renewable resources​; (4) Evaluate cost and energy consumption; (5) Avoid creating new problems in the maintenance process; and (6) Monitor the building’s performance ​regularly.

Based on P. S. Sharples (2024), several approaches can be taken in designing a net zero-carbon building. The priority should be minimising the embodied carbon that comes from materials transported until their disposal​. High-performance insulation and glazing should be installed to reduce energy consumption. Next, renewable energy options like solar, geothermal, etc., should be explored. Lastly, purchasing verified carbon offsets or investing in carbon-captured installation ​can offset the remaining carbon.

Two case studies are presented to help understand the concept of net zero carbon design in hot and cold climates. For the hot climate, the DPR Construction Phoenix Regional Office building is taken, whereas the Zero Energy Building (ZEB) Pilot House in Larvik, Norway, is explained as an example in the cold climate environment.  

Case Study 1: DPR Construction Phoenix Regional Office

1.       Zero Carbon Building Policies

Phoenix is located in the United States of America (USA). It is the capital city of the State of Arizona. USA contributes 23.83% of carbon emmision or 431.85 MtCO₂e (H. Ritchie et al., 2024). They have two similar approaches toward green building, which are Zero-Energy Building (ZEB), assessed by the US Department of Energy (DOE), and Zero Carbon Building provided by the United States Green Building Council (USBGC). These initiatives are voluntary frameworks that aim to support the reduction of GHG emissions both in new and existing buildings (D. Satola et al., 2022).

Zero-Energy Building was launched in 2015 and focused on energy consumption. It calculated the use of Heating, Ventilation, Air Conditioning (HVAC), lighting, vehicle charging, indoor transportation, domestic hot water, and plug loads. The balance between energy use and production is essential based on this framework. However, it does not specify the minimum Energy Use Intensity (EUI) requirement and the building fabric. Moreover, it does not count the embodied energy or emission as one of its scopes (D. Satola et al., 2022).

USBGC is a non-government agency that grants LEED Zero Carbon Certification; published in 2018, the Zero Carbon schema includes measuring the carbon dioxide equivalent (Co₂e). Zero Carbon building is highly energy-efficient. In addition, it aims to balance the amount of carbon dioxide emissions released on an annual basis or even reach a negative carbon level because of its renewable energy sources on-site and/or off-site (T. Usgbc, 2019).

Although Phoenix is part of Arizona State, most cities have their targets regarding building carbon emission reductions. For instance, Phoenix aims to have positive energy and materials for all new buildings in 2050 (C. O. Phoenix, 2024). Similarly, the USA projects that all existing buildings will be included in the same year. While in 2050, Arizona set the amount of carbon emissions reduction up to 208.000 MtCO₂ (A. S. University. et al., 2024).

2.       Project Description

2.1.    Project Overview

Table 1. DPR Construction Phoenix Regional Office Overview

Architect	SmithGroupJJR (architect), DNV KEMA Energy & Sustainability (Energy Design and Building Performance) Bel-Aire Mechanical, Inc. and Wilson Electric Services Corp (MEP Design-Assist Contractors) PK Associates, LLC (Structural Engineer)
Owner	DPR Construction
Year	Renovation completed 2011, First built 1972
Size	16,533 ft2 (1,536 m2)
Height	1 Story
Building Type	Class A Office 60 people
Annual Hours Occupied	2.080 (40 hours/week)
Certification	LEED BD+C v3 Platinum and Net Zero Energy Building (NZEB) certification from the International Living Future Institute
Budget	$4,571,280
Building primary motivation	1.        Cost-effective 2.        High-performing  3.        Aim for ten-year payback
Project Type	Renovation

   

(L. Reeder, 2016)

          DPR Construction renovated a neglected 1972 building as its Regional Office. It is located in Phoenix, Arizona, USA. DPR Construction also used 75% of the demolition and construction waste for the construction itself. Furthermore, this renovation is projected to meet a ten-year net zero energy investment payback (L. Reeder, 2016).

The renovation was completed in six months, from April 2011 until October 2011. After a year of evaluation of its sustainability features, in December 2012, it achieved net zero energy in operations (L. Reeder, 2016). Recently, DPR Construction purchased 16,500 metric tons of Verified Carbon Offsets certificate to neutralise the carbon emissions in their three projects, including the Phoenix Regional Office (D. Construction, 2022).

2.2.    Location and Climatic Data

Figure 1. Climatic Data of Phoenix, Arizona (Ecoclmax, 2016)

Figure 2. DPR Construction Phoenix Regional Office (Berkeley. et al., 2018)

             Based on the International Energy Conservation Code section C301, Phoenix is located in Climate Zone 2B (Ashrae, 2021). It is a harsh desert climate (L. Future, 2025) with intense sun exposure, low precipitation, and dusty environments. It has high evaporation rates that make water need to be managed efficiently.

Table 2. Phoenix Climate Condition

Location	222 N. 44th St. in Phoenix, Arizona, USA
Latitude	59.184N°N
Longitude	112.004°W
ASHRAE Design Condition	2B Hot and Dry (2021)
Avg. Year Temperature	24.2°C (DBAvg)
Coldest Month	15°C, Dec (MCDB)
Hottest Month	34.2°C, Juli (MCDB)
Avg. Precipitation	188mm
Avg. Wind Speed	2.8m/s

      (Ashrae, 2021)

3.       Building Design and Services Strategies

3.1.        Challenges and Solutions

Following the climate condition and the ten-year investment payback period target, the building strategies include maximising passive cooling and natural lighting, Optimising the building insulation and reusable material, utilising photovoltaic energy resources and water-efficient fixtures, and periodically controlling the energy used.

The passive design strategy includes deciding the orientation of the building. The doors and windows are placed on the north and east sides because the sun is less intense in those directions (L. Reeder, 2016) and 87 operable windows and roll-up doors provide natural daylight and air circulation (Berkeley. et al., 2018). Moreover, all windows are controlled by a Building Automation System (BAS) that adjusts the opening according to current climatic conditions, such as wind speed and temperature from the local airport weather station data (L. Reeder, 2016). Besides the window, solar chimneys and shower towers are also controlled by this system (Edc, 2012).

Figure 3. Cooling Tower on the East Side of the Building (Berkeley. et al., 2018)

Figure 4. An 87 Foot Long Solar Chimney Vacuum the Hot Air Outside (L. Reeder, 2016)

 Sollar Chimney is used to enhance airflow and cooling. Its zinc clad is heated on its surface and serves as a vacuum for the hot air in the interior, expelling it outside and pulling the fresh air from the window. While it happens, a shower tower and big fans help cool the air. Four cooling shower towers are made from HDPE pipes and sheet metal as the bases (Berkeley. et al., 2018). A shower head and misters on top of the tower cool the air and send it to the bottom of the pipe into the workspace (L. Reeder, 2016). Apart from its passive cooling approach, this office still provides controlled air conditioning units. BAS opens and shuts all these mechanical and passive systems so they can be adjusted accordingly.

Figure 5. Passive Cooling System and Renewable Energy Sources in The DPR Construction Building (L. Reeder, 2016)

The natural lighting system comprises 82 Sollar tubes that reduce 70% of artificial lighting (Edc, 2012) and oversized windows. Additionally, a patio is placed along the windows and acts as a connection between the outside and interior of the building. Its planted covered roof serves as a barrier to prevent dust, noise, and excessive sun exposure (L. Future, 2025). In addition, to overcome the low precipitation conditions, water efficiency strategies, including the use of efficient sanitary fixtures, drought-tolerant landscaping, and drip irrigation, are adopted (J. S. Robins, 2014).

Figure 6. Site and Roof Plan (L. Reeder, 2016)

1. V panels on the parking’s roof 2. Patio 3. Entrance 4. Solar Tubes on the existing roof 5. Solar Chimney 6.Landscape

 

3.2.        Renewable Energy and Energy Use

 According to a 2014 evaluation. The EUI is 80 kWh/m²/year, whereas the office baseline is 212.5 kWh/m²/year (L. Reeder, 2016). This means the energy consumption per metre square is lower than the average office building standard. These can be achieved because of several strategies, including adopting a shutoff button to eliminate the non-critical load. The last person in the office needs to push this button to reduce the energy used. Moreover, a monitor energy performance is available for all members to check in real-time (J. S. Robins, 2014). Domestic hot water also reduces energy consumption using a roof-mounted solar thermal system next to the solar chimney. In addition, existing inefficient mechanical units are replaced with LED light fixtures and daylight censors (Edc, 2012).

Figure 7. The use of tubular daylighting reduces 70% of energy consumption (J. S. Robins, 2014)

Figure 8. Building Energy Performance Dashboard Accessible For Occupant Helps Control Their Behavior (Berkeley. et al., 2018)

        The DPR office uses a photovoltaic (PV) energy source. PV Panels are installed on top of the parking canopy. They consist of 326-235 Wdc modules with a ten-degree tilt. The system is connected to the grid so excess electricity can be credited to the building management. Moreover, this 79 kWh solar panel system can generate 142.871 kWh. Compared to the annual energy used, this building can collect 13.255 kWh of energy back to the grid (L. Future, 2025).   

Figure 9. PV Panels on The Parking Roof, Courtesy of Gregg Mastorakos (L. Future, 2025)

3.3.        Material and Embodied Carbon

Material selection is closely related to Life Cycle Assessment (LCA). LCA is used to calculate the building's performance in terms of carbon emissions throughout its life cycle, from material extraction to end-of-life processes, such as recycling (V. Rodrigues et al., 2018). In this case, the DPR construction renovation project recycled the demolition material and maintained most of the existing structure. For example, the concrete masonry block wall, structural steel, and roofing are retained. This resulted in a reduction of landfill waste by 252 tons. Additionally, it used bamboo for the screen wall enclosing the building, which accounted for 3.35% of the material cost (Edc, 2012). Bamboo, Timber and bricks are examples of regenerative materials that are low in carbon emission (P. Un Environment et al., 2023).

Native desert plants such as Vines, Palo Verde trees, Agave Cacti, Desert Spoon Shrubs, and Hesper aloe are used as they are more tolerant of drought (L. Future, 2025).

3.4.        Lessons Learned

The building aims to reduce energy consumption by optimising the natural resources in the desert environment. However, collecting airborne dirt on the water filter in the cooling tower is unavoidable. A regular cleaning process is needed to overcome this issue (L. Reeder, 2016). In addition, automated windows produce noise that affects occupant comfort (J. S. Robins, 2014).

Strategies to decrease energy consumption depend on the occupant’s participation. For instance, pressing the shutoff button to reduce non-critical load, participating in daily energy monitoring, and tolerating the temperature threshold since the building adapts a passive cooling system. These strategies demand continuous campaigns and education from the top management.

4.       Building Performance and User Satisfaction

 

Figure 10. The Comparison between Predicted, Actual Energy Use, and Actual Energy Generated from Sollar Panel from January 2012 until February 2013 (J. S. Robins, 2014)

The graph shows that the energy use was lower than predicted in the first year of operation. Moreover, there was an energy surplus between the energy generated from Photovoltaic panels and the energy consumption. This surplus can be distributed to the grid, therefore accelerating the return on the investment from the ten-year target to only an eight-year (L. Future, 2025).

Figure 11. 2014’s Energy Used (L. Reeder, 2016)

Figure 12. Energy used between 2012-2013 (J. S. Robins, 2014)

         Mechanical load accounted for more than 50% of energy consumption. Additionally, in the 2012-2013 evaluations, fans were primarily used in the summer. However, computer plug load consumption remained stable throughout the year, and in terms of water conservation, using water-efficient fixtures saved 19% of water consumption.

5.       Conclusion

The Zero-Energy Building policy was reflected in the DPR Construction Phoenix building objective. It is focused on minimising energy use by optimising the site’s opportunities, such as solar radiation and wind. As a renovation project, it reuses as much of 93,7% of the existing building features as possible to lower the carbon emmision. It also monitored daily energy used according to microclimate conditions as well as to encourage occupants’ participation in reducing the electricity. Combining energy-efficient strategies and renewable energy resources resulted in 8 years of investment return.

Case Study 2: ZEB Pilot House Larvik, Norway

1.       Zero Carbon Building Policies

Norway produces 0.15% of carbon emissions worldwide (H. Ritchie et al., 2024). It has become one of the lowest emittent countries because of its hydropower, which comprises 95% of its energy resources (R. S. Jorge et al., 2013). Norway established a Zero-Energy Building (ZEB) scheme in 2015. It uses Green House Gas (GHG) reduction as the key indicator that focuses on the whole life cycle both for operational and embodied carbon. Furthermore, in 2050, 95% of GHG emissions are expected to reach below the 1990 level for all types of buildings (D. Satola et al., 2022).

The ZEB initiative was introduced by a research organization which suggests 5 levels of ZEB according to the ambition level, including (1) ZEB-O-EQ, which focuses only on the operation of the building, excluding equipment or plug load; (2) ZEB-O, including all operational; (3) ZEB-OM, adding the materials embodied carbon; (4) ZEB-COM, considering the GHG emission that comes from the construction process as well; (5) ZEB-COME encompasses all aspect, where the emmision can be offset by the use of renewable energy (D. Satola et al., 2022).

2.       Project Description

2.1.        Project Overview

Figure 13. ZEB Pilot House, Larvik, Norway (Archdaily, 2015)

            The second case study is in Norway. It is a two-story house for up to five members, part of a Zero-Emission Building Pilot project in Norway. It aims to achieve ZEB OM + Electric cars, where construction operations and materials production emissions are balanced with the building's renewable energy. Plus, supplying the user’s electrical vehicle. This building was completed in 2014 at 665 thousand US dollars for a 200m² house. This research project has no occupants. Therefore, the performance result may vary in the actual context (A. Sørensen et al., 2017).

Table 3. Project Overview

Architect	Brødrene Dahl (energy concept), Optimera (building construction), Snøhetta (architect), and the ZEB Research Centre (energy and GHG emissions)
Owner	Brødrene Dahl AS and Optimera AS
Year	2014
Size	200m2 (2,152 square feet)
Building Type	Single-family residential building. 4-5 member
Certification	ZEB-OM Classification The European Union Prize for contemporary architecture- Mies van der rohe award
Budget	5.8 million NOK (or approximately $665,000)
Building primary  motivation	Comfort: indoor air quality and daylight, environmental performance.
Project Type	New construction, ZEB-OM + electric car
(A. Sørensen et al., 2017)

2.2.        Location and Climatic Data

Figure 14. ZEB Pilot House Top View (A. Sørensen et al., 2017)

Figure 15. Larvik Climate Zone (M. Manni et al., 2022)

Located in Ringdalveien 18, 3270 Larvik, Norway, this building is in a Temperate Oceanic Climate based on the Köppen-Geiger climate zone. February is the coldest month when the temperature drops to -2.8°C (D. Climate, 2015).

Table 4. Larvik Climate Condition

Latitude	59°12’N
Longitude	10°15’E
Köppen-Geiger	Cfb, Temperate Oceanic Climate
Avg. Year Temperature	7°C (DBAvg)
Coldest Month	3.9°C, Jan (MCDB)
Hottest Month	19.5°C, Juli (MCDB)
Avg. Precipitation	974mm
Avg. Wind Speed	3.7m/s

(D. Climate, 2015); (A. Sørensen et al., 2017)

 

3.       Building Design and Services Strategies

3.1.        Challenges and Design Solutions

 

re 16. ZEB Pilot House Design Strategy (A. Sørensen et al., 2017)

Several strategies have been applied in the ZEB Pilot House. Still, two main strategies in a cold-climate building are applied: creating a high-performance building envelope with good insulation and air tightness to reduce energy loss and minimize the energy used for the heating system​. Moreover, good indoor air circulation and temperature are also among the project’s priorities.

Figure 17. Thermal Protection of The Building Envelope on The North-West Facing Tilted Wall (A. Sørensen et al., 2017)

The fabric and insulation approach includes utilising 350 mm of glass wool and installing good U-values windows, doors, roof, walls, and floor to ensure air tightness. Although the building is oriented to the south-east, the big window on the north-south is covered by solar protection, whereas the south side utilizes massive exterior cladding wood to prevent heat. Also, a reused brick wall in the atrium adds some thermal mass. On the second floor, aspen was used to handle the humidity by being installed as part of the wall cladding. In total, nine different wall structures are used. Besides reused bricks and glass wool, natural stone, timber, and low-carbon concrete are also applied. Thermal resistance also increased when a crawl space is provided underside the floor, which is mounted by reflective films (A. Sørensen et al., 2017). 

Table 5. U-Value Coefficient in The Building’s Insulation (A. Sørensen et al., 2017)

The heating load is 80% covered by a ground source to a water heat pump, whilst 20% comes from a solar thermal collector on the roof. In addition, heat recovery from air and grey water is collected and reused. The figure below shows that at least six flows distribute water and air to the building.

Figure 18. The Energy Supply Comes from Two Main Sources, Solar Collector and Ground Source to Water Heat Pump (A. Sørensen et al., 2017)

The heat is distributed through an underfloor heating system, which has only one radiator on each floor. Additionally, the ventilation system uses grills and exhaust air heat pumps. Both supply heating and cooling that are connected to a heat exchanger. Besides, all rooms have at least one window that can be opened during the warm season (A. Sørensen et al., 2017).

Figure 19. Left: Shower Drain Shows One of The Grey Water Heat Recovery Mechanisms. Right: Accumulator Tank as Outside Grey Water Heat Recovery System (A. Sørensen et al., 2017)

            Another strategy is the water-efficient fixture. A 5,000-liter tank of rainwater collection is provided for toilet flushing and irrigation (T. R. R. Writer, 2021). In addition, it has a controlled lighting and heating system that can be adjusted as needed using smart home devices connected to the website to reduce energy consumption.

Figure 20. Control System Panel for Solar Collectors (A. Sørensen et al., 2017)

3.2.        Renewable Energy and Energy Use

            The photovoltaic system produces 19,200 kWh/year. It comprises 150 m² solar panels with a 19-degree tilt and is oriented -45 to the southeast side to optimize sun exposure. This renewable energy is connected to the local electricity grid and battery bank. After eight years of observation, the energy needed is 17,348 kWh/year. Still, the demand for electricity from PV systems is reduced due to the energy generated from other sources, namely ground source and solar collectors. Thus, only 7,142 kWh of electricity is taken from PV; the rest is delivered to the grid.

Figure 21. Grid-connected solar PV System (A. Sørensen et al., 2017)

            The battery bank (48V at 600Ah) aims to increase the PV system's economic value. Excess energy from PV-generated electricity can be converted to a selling price that accelerates the return on investment of the construction cost.

Table 6. A Balance of Energy Generated from The PV System and Other Heat Sources against Energy Need (A. Sørensen et al., 2017)

 

3.3.        Material and Embodied Carbon

Over its 60-year lifetime, this building emits 2,650 kgCO₂ eq. 36% comes from operational energy use, while 52% comes from the building material. Additionally, 12% are electrical-related emissions (A. Sørensen et al., 2017). It was built with high-quality materials and a decent way of working, ensuring that constant renovation will not be needed during its lifetime (V. Vemula, 2021). According to A. Sørensen et al. (2017), who cited Rosochacki (2014), said that the building's structural parts, such as walls and insulation, had the highest emissions. Therefore, the fabric’s material choices were carefully considered.

Figure 22. Material Choices to Reduce Carbon Emissions and Improve Insulation (A. Sørensen et al., 2017)

Material choices are as follows: (1) Reused bricks in the atrium can minimise carbon emissions compared to a new one; (2) timber and fibre-based floor plate; (3) swimming pool made from reused steel container; (4) gabion or other natural stone and timber as an exterior facade; (5) low carbon concrete is also adopted, especially the use of strip foundation, to reduce the carbon emissions.

3.4.        Lessons Learned

As the project is a pilot project conducted by a research initiative, gaining a complete and correct Environment Product Declaration (EPD) from subcontractors and producers was challenging. Moreover, it is a concern that the project investment is too high to be adopted in an actual residential area. It also employs various digital tools in practice, namely, Building Information Modelling (BIM), SimaPro, and Ecoinvent, which may seem intimidating for some design teams and homeowners. The ambition of achieving ZEB-OM closely depends on the intensity of electric vehicle use. Since no actual user occupied the house, an exact measurement can not be analysed (A. Sørensen et al., 2017)

4.       Building Performance and User Satisfaction

 

Figure 23. Comparison Between Monthly Energy Generated and Energy Needed Plus PV Solar Fraction (A. Sørensen et al., 2017).

            This research building has been evaluated for eight years (V. Vemula, 2021). The building needs 17.348 kWh of energy per year, or EUI 86,1 kWh/m2. The remaining demand for delivered energy was calculated to be 7,142 kWh of electricity per year, with the highest solar fraction in between May to August (A. Sørensen et al., 2017).

Table 7. Investment Payback Time Calculation (A. Sørensen et al., 2017)

            In the future, the building investment will cost 5.6 million NOK, or 1 million more expensive than the Norwegian building code. However, due to the self-sufficient energy generated and excess energy income, this building is projected to achieve 35 years of investment payback period.

Figure 24. The Carbon Emission Balance Comparison from Renewable Electricity, Operational and Embodied Carbon (A. Sørensen et al., 2017)

         Regarding carbon emissions, 36% of emissions come from operational energy use, while 52% is from embodied carbon and replacements. Plus, 12% is the electric vehicle-related emissions. A reduction of 7,600 km of electric car use needed to be done to balance the emissions (A. Sørensen et al., 2017).

5.       Conclusion

In cold climates, the capacity of material to prevent heat loss is crucial. The compactness of the building will also determine how much energy is used to heat the surface. The more compact the building is, the less energy will be used (S. Pelsmakers, 2015). Furthermore, well-insulated fabric and reusable heat can be utilised to reduce energy consumption.

Comparative Analysis for Both Case Studies

The case studies show significant differences between hot and cold climates, mainly from the U-value and R-value of the insulation. According to S. Pelsmakers (2015), the U-value is the heat transfer rate through the material, whereas the R-value is a material’s resistance to heat flow. The lower the U-value, the less heat is transferred through the material, while the higher the R-value, the more it is in resisting heat transfer (S. Pelsmakers, 2015). Therefore, improving the performance of the insulation based on the climate condition will reduce the energy consumption (I. Nardi et al., 2014).

DPR Construction office, located in the hot desert climate, opts for passive cooling strategies. Moreover, based on I. Institute (2025) The 2012 International Energy Conservation Code (IECC) Guide for Homes in Arizona, it is suggested that the R-value minimum for walls is 13 m²K/W. The DPR Office case study shows that the wall's 19 m²K/W R-value achieves user satisfaction and can reduce energy consumption.

 Table 8. The 2012 IECC Compliance Guide for Homes in Arizona

(I.Institute, 2025)

Meanwhile, the Larvik house, in the cold climate, opts for a U value for windows and door is 0.75 W/m²k. According to Ndvk (2023), the required thermal transmittance for doors and windows is suggested below 1,2 w/m²k. It means that the windows and doors in the second case study have already met the insulation standard in a cold climate area.

Both studies emphasise embodied carbon. However, in the DPR Construction Office case study, LCA was not included in the LEED assessment. In contrast, the ZEB Pilot House emits 13,2 kgCO2 eq/m2 per year, which is predicted to achieve net zero carbon within 60 years accumulated with the operational carbon and the use of electric cars. However, the future occupant need to limit their travel time by 7,600 km. Embodied carbon significantly contributes to the total carbon emission (A. Houlihan Wiberg et al., 2014). Therefore, precise EPD and LCA calculation should become crucial to net zero carbon building.

The case study had a metered system that can be regularly monitored via a website. It helped measure daily energy use and encouraged occupant participation, eventually creating a new habit of adjusting to a more energy-conscious lifestyle.

Both case studies demonstrate the feasibility of achieving net-zero carbon buildings in different climates using various strategies. The DPR office highlights the effectiveness of renovation, passive cooling systems, and plug load reduction. Meanwhile, the ZEB Pilot House showcases the benefits of new construction, focusing on minimizing both operational and embodied carbon.​

​Table 9. Comparison between Hot Climate and Cold Climate Buildings

Comparison	Hot Climate	Cold Climate
Building	DPR Construction Phoenix Regional Office​, USA	ZEB Pilot House Larvik, Norway
Climate	2B, Hot and Dry (ASHRAE, 2011)	Sandefjord, Torp warm and  temperate (Koppen-Geiger)
Avg. Temperature	24.2°C	7°C
Building Type	Office, 60 people	Single-family residential building. 4-5 member
Project Type	Renovation	New Construction
Building Motivation	Cost-effective, High performing, 10 y PBP	ZEB-OM + electric car
Minimize Embodied  Carbon	1. Reuse 93,7% original shell and structure 2. Renewable material: wood	1. Reuse brick, steel container,  railroad sleepers 2. Renewable material:  timber, fibre, stone 3. Low-carbon material: Low-carbon concrete 4. LCA, EPD
Minimise Operational  Energy Consumption	1. Envelope R-Value: Walls:19   Roof:43  Windows: 0.15 (U-factor) 2. Plug load reduction and monitoring	1. Envelope U-Value (W/m2K) Walls: 0.111 Roof: 0.084 Windows&Doors: 0.75 2. Lighting & heating control  system
Maximise Use of Renewable Energy	PV energy generated Thermal energy: Sollar collector	PV energy generated Thermal energy: ground source,  solar collector, grey water heat recovery, air-to-water heat pump
Offset Remaining  carbon emission	6,500 metric tons (cumulative)	-
Investment Payback Period	8 Years	35 years
Net Zero Carbon Period	9 years	60 years
Thermal Comfort	20 °C (winter) 27 °C (summer)	22-degree celsius

         The comparison emphasizes the importance of context-specific design considering climate and building type, a holistic approach addressing embodied and operational carbon, and integrated strategies combining passive and active measures with renewable energy and carbon offsetting.​ By learning from these examples and adapting strategies to specific contexts, the building industry can strive towards a future with net-zero carbon buildings, contributing significantly to global GHG emission reduction goals.​

References

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2.       Ashrae (2021) ASHRAE CLIMATIC DESIGN CONDITIONS 2009/2013/2017/2021. Available at: https://ashrae-meteo.info/v2.0/ (Accessed: 1 January 2025).

3.       Berkeley. & Environment., C.O.B. (2018) A Living Laboratory, DPR Construction Phoenix Regional Office. Available at: https://cbe.berkeley.edu/wp-content/uploads/2018/07/DPRhq.pdf (Accessed: 2 January 2025).

4.       Climate, D. (2015) Larvik Climate. Available at: https://en.climate-data.org/europe/norway/vestfold/sandefjord-9925/ (Accessed: 11 Januari 2025).

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6.       Ecoclmax (2016) Climate of the United States. Available at: https://www.ecoclimax.com/2016/08/climate-of-united-states.html (Accessed: 2 January 2025).

7.       Edc. (2012) 'RISING from Phoenix's Ashes', Environmental Design + Construction, 15(6), PP. 24-26.

8.       Finnegan, D.S. (2024) 'Sustainability in Construction Practice' [Recorded lecture]. ARCH747:  Net Zero Carbon Design. University of Liverpool. 29 October. Available at:   https://canvas.liverpool.ac.uk/courses/77003/files/11338657?module_item_id=2080533 (Accessed: 29 October 2024).

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