Buildings Using Passive Design Strategies for Energy Efficiency by naresh

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Pitch

Passive design, an approach to building design that uses the building architecture to minimize energy consumption.

Description

Summary

Using passive design building form and thermal performance of building elements (including architectural, structural, envelope and passive mechanical) are carefully considered and optimized for interaction with the local microclimate. The ultimate vision of passive design is to fully eliminate requirements for active mechanical systems (and associated fossil fuel-based energy consumption) and to maintain occupant comfort at all times

Even though we may not achieve the ultimate passive design vision on every building, implementing the passive design approach to the fullest extent possible will lower building energy use. Building shape, orientation and composition can improve occupant comfort by harnessing desirable site specific energy forms and offering protection from undesirable forms of energy. Through properly applied passive design principles, we can greatly reduce building energy requirements before we even consider mechanical systems.

Category of the action

Building efficiency: Physical Action

What actions do you propose?

The proposed actions are:

Passive Design Strategies

With many passive strategies, there is a trade-off between heating performance and cooling performance. The building type and operation determine which strategies will have the best overall impact on energy performance.

1 Passive Heating: Using building design to harness solar radiation and capture the internal heat gains is the only passive way to add free thermal energy to a building. Passive solar heating combines a well-insulated envelope with other elements that minimize energy losses and harness and store solar gains to offset the energy requirements of the supplemental mechanical heating and ventilation systems.

Elements that contribute to passive solar heating include the following:

1. Orientation
2. Building shape
3. Buffer spaces and double facades
4. Space planning
5. High-performance windows (clear, low-e)
6. Mixed-mode heat recovery ventilation (HRV)
7. Low window to wall area ratio (N/E)
8. High window to wall area ratio (S/W)
9. Operable external shading
10. High-performance insulation
11. Thermal mass
12. Minimized infiltration

2. Passive ventilation

Passive ventilation strategies use naturally occurring air flow patterns around and in a building to introduce outdoor air into the space. Wind and buoyancy caused by air temperature differences create air pressure differences throughout occupied spaces. Buildings can be designed to enhance these natural air flows and take advantage of them rather than work against them.

The passive elements that contribute to natural ventilation include the following:

1. Operable windows
2. Buffer spaces and double facades
3. Building shape
4. Space planning
5. Orientation
6. Strategic architectural features
7. Openings to corridors and between otherwise separated spaces
8. Central atria and lobbies
9. Wind towers

3 Passive Cooling

Passive cooling strategies prevent the building from overheating by blocking solar gains and removing internal heat gains (e.g. using cooler outdoor air for ventilation, storing excess heat in thermal mass).

Elements that contribute to passive cooling include the following:

1. Fixed/operable external shading
2. Thermal mass
3. Low window to wall area ratio (S/W)
4. Passive ventilation
5. Nocturnal cooling
6. Stacked windows
7. Passive evaporative cooling
8. Earth-tempering ducts

Nocturnal cooling uses overnight natural ventilation to remove heat accumulated in the building mass during the day. The cooler nighttime air flushes and cools the warm building structure/mass.

4 Daylighting

Daylighting maximizes the use and distribution of natural diffused daylight throughout a building’s interior to reduce the need for artificial electric lighting.

The features which contribute to a daylighting strategy include:

1. Space planning
2. High ceilings paired with tall windows
3. Window size and placement (window to wall area ratio)
4. Interior surface colours and finishes
5. Strategic architectural features
6. Light shelves
7. Skylights and light tubes
8. Clerestories

5. Applying the Strategies: Commercial

Commercial buildings have different characteristics from residential buildings, such as reater internal heat gains from equipment and lighting, higher ventilation requirements, and different occupancy trends. Commercial buildings benefit from passive cooling, but in the Vancouver climate, design must strike a balance between heating and cooling performance.

Specific passive approaches that will improve the overall energy performance of commercial buildings in Vancouver include:

• Carefully detailed and constructed high-performance insulation in the envelope with minimal thermal bridging, including exterior walls and roofs.
• Solar gain control using either high-performance windows with low shading coefficient (tinted or reflective) or clear high-performance windows with a low-e coating in  combination with operable external shading to block solar gains during summer and shoulder seasons and admit solar gains during winter.
• Window to wall area ratio limited to <50%.
• Double facades with operable shading elements and operable windows to act as thermal buffer spaces, preheat ventilation air in the winter, and block solar gains and provide natural ventilation in the summer.
• Building shape and massing that enhances natural ventilation and daylighting, ideally with central atria and ventilation towers.
• Thermal mass on the interior side of the insulation, located in the floors, external walls, and walls between adjoining units (i.e., party walls).
• Passive cooling strategies, such as nocturnal ventilation to pre-cool spaces during summer and ventilation air intakes located in cool areas and delivered to the building using earth tubes.
• Air- and moisture-tight envelope.

6. Applying the Strategies: Residential

In the Vancouver market, the vast majority of residential developments are medium- and high-rise towers. Residential spaces have night-time occupancy and relatively low internal heat gains (aside from intermittent cooking), which results in a heating-dominant residential energy profile in the Vancouver climate.

• Specific passive approaches that will improve the overall energy performance of residential buildings in Vancouver include:
• Carefully detailed and constructed high-performance insulation in the envelope with minimal thermal bridging, including exterior walls and roofs.
• Clear, low-e, high-performance windows in combination with operable external shading to block solar gains during summer and admit solar gains during shoulder seasons and winter

Note: any building in which the window to wall area ratio is greater than 50% will be challenged to achieve higher energy performance

• Unconditioned, enclosed buffer spaces (not regularly occupied) that cover the perimeter of the space, fitted with operable windows to provide natural ventilation from the exterior to the interior space when desired.
• Thermal mass on the interior side of the insulation, located in the floors, external walls, and walls between adjoining units (i.e., party walls).
• Compact and simple form.
• Air- and moisture-tight envelope.
• Mixed-mode ventilation using HRV during the winter only and passive ventilation throughout the rest of the year.

Who will take these actions?

The key actors are:

Governments, Local government, International organizations, Environmentalist, Economist, Researchers, Sociologist, NGOs, INGOs, Technical institutes, Energy sector organizations, Industries,  Communication medias, Private sector, and other concerned parties.

Where will these actions be taken?

Any part of the worlds especially developed countries.

How much will emissions be reduced or sequestered vs. business as usual levels?

Yet not calculated but depending upon the number of building constructed.

What are other key benefits?

The key benefits are:

1. Passive elements and strategies effectively expands the range of outdoor conditions under which buildings can remain comfortable without active systems.
2. When outdoor conditions fall within the extended passive zone, a building that incorporates all of these passive strategies will be comfortable without mechanical heating or cooling; when conditions fall outside of the zone, the building must rely on active systems to maintain thermal comfort.

3. Passive design enables buildings to maintain occupant comfort  throughout more of the year using less energy.

What are the proposal’s costs?

Proposal cost will be determined by the type of project, site of project, duration of time, implementing agencies, type of technology used in the project site and number of building constructed.

Time line

Depending on the nature of project, site of project, amount of budget, type of technology used in project site. Generally, the project time line in short term 5-15 years for baseline survey, creating awareness of local communities, building networks, making policies, designing and construction of the buildings and Research. After, 15 years, in medium term 15-50 years, implement the project activities timely and monitor regularly. After, 50 years, long term evaluates the project goals and outcomes.

Related proposals

References

vancouver.ca/files/cov/passive-design-large-buildings.pdf