• Which factors should be considered during HVAC planning? How does the design process work with these factors?
When beginning HVAC planning for a space, our engineers are focused on the well-being of the future occupants. The team considers thermal comfort, interior air quality, energy performance, and space quality. Their planning methodology is based on data and analysis that is repetitive and replicable over our project profile, and therefore offers proven results.
• Are there any natural solutions applicable to HVAC considering maximum utilization of daylight for lighting?
There are natural solutions applicable to HVAC including natural ventilation, evaporative cooling, economizers modes, thermal mass, night purging, as well as other technology-based like radiant systems or use of phase change materials. Stantec utilizes a breadth of HVAC interventions and design strategies that can be applied to achieve passive systems in the built environment. On the National Renewable Energy Laboratory (NREL) in Golden, Colorado, Stantec designed
a 60-foot-wide building floor plate allowing us to use an advanced light bouncing device (LightLouver) to daylight 90% of all occupied work spaces year-round and naturally ventilate the entire floor plate through operable windows.
• How should ‘passive climatization’ be defined, used, and applied?
Combining passive and climatization may appear to create an oxymoron. Passive design takes advantage of the climate to maintain a comfortable temperature range in a space and aims to eliminate the need for auxiliary heating or cooling. In contrast, climatization is the use of active design interventions and / or technology to improve thermal comfort. However, together passive climatization ensures that the space fully utilizes the passive qualities of the built and natural environment to provide thermal comfort. The building massing, orientation, thermal mass, insulation, shading, glass quality and quantity, phase change materials, cool rooves, natural ventilation are all strategies that are critical to passive climatization.
Our projects for the NREL and the Sacramento Municipal Utility District’s (SMUD) operation center used a variety of passive strategies to supplement active heating and cooling systems. For NREL, we raised the building to create a rat / mat slab to compensate for the expansive soil. Stantec engineers used this space to create a thermal labyrinth to pre-heat or pre-cool air going into the building – an inventive active passive strategy using a site-specific condition to save energy. During the summer, cold night air is stored in the labyrinth and used during the day to pre-cool the building. In winter, warm air coming from the data center and the transpired solar collectors is stored in the labyrinth to pre-heat the air for the next day. For the SMUD project, we extensively shaded the windows using micro louver technology to cut off all heat gain into the space through the windows year round. In both projects (NREL & SMUD), the buildings were oriented along the east-west axis to allow for maximum daylighting penetration into the building and to minimize solar gain and glare through the use of low cost and effective shading strategies.
• What kind of materials / methods are applicable for saving energy through thermal insulation, and how? How the efficiency can be achieved?
Thermal insulation offers a significant opportunity for energy savings using both natural and engineered materials like closed cell insulation applied to construction and equipment. Most importantly, installation must be properly executed. Thermal bridging occurs across a building envelope when there is a pathway for heat gain or loss through any material in the structure that is more conductive than the insulation surrounding it. The envelope of a well-insulated building can perform poorly if attention is not given to key connection points within a building structure / envelope such as roof / parapet connections, floor / wall connections, window frames, and slab / wall connections. For example, chilled water systems insulation must ensure equipment is sealed correctly to avoid condensation that would damage and reduce the system’s effectiveness. The NREL and SMUD projects were tightly focused on mitigating heat loss and gain through the building envelope. Thermal bridging studies were done to ascertain how and where to insulate to effectively mitigate thermal bridges.
• Would you tell us about the integration of HVAC systems into renewable technologies and sustainable structures?
There are numerous renewable energy technologies that can be used to heat and cool buildings within the HVAC field. Solar thermal collectors harvest heat from the sun and produce hot water for heating spaces & domestic hot water. They can also be integrated with absorption chillers to produce cooling. Geothermal systems exchange energy with the ground and are used in heating and cooling applications such as heat pumps and absorption chillers. Many engineers classify geo-exchange with heat pumps as a purely renewable source however our Stantec experts believe that only 70% of the energy used comes in the form of renewable energy from the ground.
• What is the role of the building shell in natural air conditioning or how
should it be?
The building shell / envelope is a fundamental element in the design of naturally ventilated spaces, the consideration for the location of openings and interaction of intakes and exhaust routes. Since natural ventilation has a limited capacity to cool, the careful design of the building shell or facade is essential to avoid imposing greater solar loads on the interior space than necessary.
• HVAC systems are one of the most important technologies that provide. Aesthetics are just as important. How does one balance the functionality of providing comfort with the aesthetics of a space?
While the HVAC industry is trailing other industries in combining the functional aspects of the HVAC system with the aesthetic requirements of a space, it is moving toward a more balanced approach of functionality and aesthetics. For example, the ‘nest’ thermostat has become a cool (no pun intended) system component which combines user-friendly functionality and advanced control algorithms in an aesthetically pleasing design. Some of the new energy codes force the designer to decouple the ventilation systems from systems that serve the interior load and that opens opportunities to use more energy efficient and structurally integrated HVAC systems such as radiant ceiling & chilled beams. As owners are now actively embracing energy efficiency in the design of their buildings, they have become more willing to pay for systems that are both efficient and aesthetic.
• Would you tell us about the use of different HVAC solutions depending on the project type (housing, commercial spaces, etc.)?
The variations in HVAC solutions can be quite different across the different building sectors. Residential users are looking for tighter personal control over their environment. While those in a commercial building are more accepting of lessor control over their thermal comfort. There is a trend to design commercial systems to allow for greater occupancy-based control that would enhance comfort and reduce energy usage. There is a lot of research currently taking place in personal comfort technologies, thermal comfort wearables, comfort chairs, and more. Hospitals’ HVAC solutions are more driven by air change requirements with the need for a rigorous filtration system to provide a clean environment for patients and staff.