HydroShell FAQ

Question 1

How much does a Hydronic Shell system cost?

Accepted Answer

For most multifamily buildings, the Hydronic Shell will have a lower total installation cost compared to any other heating, cooling, and ventilation retrofit solution. This is mainly because it's a single prefabricated solution that minimizes site labor and avoids costly work within occupied apartments. The cost of the high-performance central equipment is amortized over many apartments and benefits from load diversity to reduce the total installed capacity. The lower installation cost and lower energy and O&M costs result in attractive payback periods. In many cases, projects can be financed with long-term loans with annual operating cost savings that are greater than the annual loan payment.

Question 2

What is the new outer shell made of?

Accepted Answer

The Hydronic Shell HVAC system can be integrated into a wide variety of different facade products from many different manufacturers, allowing for virtually unlimited options for materials, appearance, and performance. This allows the design of the shell to be tailored to the specific needs of each project.

Question 3

Is the Hydronic Shell suitable for all building types?

Accepted Answer

The Hydronic Shell is suitable for many different building types, for retrofits as well as new construction. However, our initial focus is on multifamily retrofits and modular new construction. There are some multifamily building characteristics that may not be suitable for overclad retrofits, such as buildings with historic facades or facades that are already extended to the limit of the lot line.

Question 4

Does the Hydronic Shell pose a risk of fire and smoke spread between floors?

Accepted Answer

The cavity formed between the new and existing facades is separated by firestopping between floors and adjacent apartments to prevent the spread of fire and smoke. Fire testing standards, such as NFPA 285, can be used to demonstrate the fire safety of any construction assemblies specific to a given project.

Question 5

Can a dwelling unit be conditioned completely from the exterior?

Accepted Answer

For the vast majority of multifamily buildings, the answer is yes. The floorplates are not deep enough to require an interior conditioning system. Other spaces within the building, such as interior corridors and amenity spaces, may require separate systems within the building. When applied to other building types such as office buildings, the Hydronic Shell may be used for perimeter loads only, while separate interior mechanical systems provide cooling and ventilation to interior zones.

Question 6

What about condensate management?

Accepted Answer

Condensate management can be a big challenge for retrofit projects. One major advantage of the Hydronic Shell system is that it is non-condensing. We run higher chilled water temperatures so the HydroBox provides sensible cooling only. All dehumidification is provided by the fully conditioned and dehumidified ventilation air. Controlling dehumidification separately from sensible cooling also provides for better thermal comfort. Higher chilled water temperatures means the heat pump operates more efficiently, and eliminating the need for pipe insulation lowers costs.

Question 7

What are the maintenance requirements?

Accepted Answer

The Hydronic Shell system does not require any regular maintenance within the apartments. The only moving parts at the apartment level are the hydronic control valve and the HydroBox fan, both of which can be easily accessed by removing the top grille on the rare occasion that replacement is needed. The rooftop air handling units and heat pumps are standard equipment that can be maintained through ordinary maintenance contracts or by the building operations staff.

Question 8

What are the structural requirements?

Accepted Answer

The overclad facade panels tie back to the existing building structure. The specific connection details will vary from project to project. In some cases the panels will connect directly to exposed components of the existing structure, such as exterior masonry or exposed floor slabs. In other cases, portions of the existing facade may require removal to expose the structural connection points. Choosing lightweight materials for the outer shell will ensure that the existing structure can support the additional load. The HVAC components within the shell will contribute a very small portion of the overall weight.

Question 9

Is there a risk that the pipes will freeze?

Accepted Answer

The pipes within the shell are in a heated space on the interior side of the new insulation, eliminating the need for freeze protection measures in most cases. However, the piping on the roof may be exposed to freezing conditions, in which case freeze protection measures would be recommended, such as electric heat tracing on the exposed piping or circulating a glycol mixture. The risk of freezing and appropriate prevention measures should be evaluated on a project-by-project basis.

Question 10

Can the system provide simultaneous heating and cooling?

Accepted Answer

The hydronic system can be implemented as a 2-pipe or 4-pipe system. A 4-pipe system enables both heating and cooling to be available to all units year-round. The central heat pumps in a 2-pipe system can be zoned by facade exposure such that individual heat pumps can switch between heating and cooling in response to the sun's orientation. Additionally, the ventilation air can be supplied at a lower temperature to provide cooling capacity to each unit while the hydronic system is in heating mode.

Question 11

Are there any existing Hydronic Shell installations?

Accepted Answer

There are many examples in Europe and North America of overclad retrofits using prefabricated facade panels. However, the Hydronic Shell HVAC system is a new technology that is in the development and testing stage. Stay tuned and follow us to learn about new developments and progress towards commercialization.

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