Luxury Living at the Top: Avoid Mistakes when Adding a Penthouse to a Commercial Building

The placement of a penthouse on top of a commercial building is becoming more attractive and common.  These units are often highly sought after by luxury homeowners seeking a unique living experience with the convenience of being located in a central business district. In comparison to the commercial spaces below, the top-floor homes can offer luxury, design, high-end finishes, exclusive access, exceptional views and other features to appeal to designers and homeowners alike.

While the allure of a penthouse on top of a commercial building is undeniable, we as mechanical and energy engineers extend our focus far beyond the luxury finishes and stunning views. We take a deeper dive into the building’s infrastructure, considering the intricate systems that make such a project feasible, especially when it is so distinct from the rest of the building. From HVAC systems, plumbing, and electrical load management to ensuring proper structural integrity, our role involves examining the internal and invisible operations of the building.

DMA Engineering came to the rescue to correct architectural design problems in a luxury penthouse on top of a commercial building.

We want to share the story of how our DMA team turned around a frustrating and unsatisfactory living situation for some new penthouse owners in the Cherry Creek district in Denver.  Spoiler alert: This story has a happy ending of the homeowners’ relief and satisfaction. They said that their home system would never have worked if DMA had not stepped in to perform such a thorough commissioning of the system.

The Challenge: Luxury space limited by commercial exterior design.

The design for this space was constrained by the original architectural design and the shortfall in the original building’s MEP consultant’s understanding of the elevated expectations of luxury residential spaces versus commercial spaces.  The building’s architectural design should have anticipated the sophisticated mechanical and energy systems required by the addition of a penthouse and how they would integrate with the building’s existing framework, but it did not.

Our challenge was to design a mechanical system that corrected the mistakes made by original design team of the building to meet luxury clients’ expectations within the limitations of the height and structure of the ceilings, exterior windows, interior sill and header heights, and other fixed parameters.

Here are some examples of the problems we at DMA encounter and the solutions we provided. We share these examples with you in the architectural design community in the spirit of avoiding similar mistakes and client dissatisfaction in the future.  

Design Limitations: Importance of keeping form and function in mind—inside and out.

Problem: Because the original architect drew the building from outside perspective and then went to an interior design, mechanical systems did not fit well into the available interior spaces.  For example, the mechanical system was a 4-pipe hot and chilled water system that served fan coils with a dedicated outside air system providing fresh air. There could be no access panels in the space to access dampers or Variable Air Volume (VAV) boxes in the ceiling of the space. 

DMA Solution: We worked with ownership, the Architecture firm KGA and the general contractor MESA Properties to develop innovative ways to house the mechanical systems. DMA proposed a mechanical platform over the master bathroom that would allow for a lowered ceiling in this space only.  This redesign eliminated the access panels in the space and gave the master bath the finish level the architect was aiming for.

Floor and Ceiling Spaces: Uneven spaces and floors hindered good heating and cooling.

Problem: We needed to have a way to heat and cool the space at the same time, and a full concrete radiant floor system could not be utilized due to the uneven floor and the incorrect floor heights for the elevator and stairwell exits.  In addition, the ceiling (in the commercial space) below this potential radiant flooring was insulated as plenum space and worked against an effective radiant floor system. 

DMA Solution: We researched and analyzed radiant floor systems that would allow the fan coils to cool the required spaces while the radiant floor maintaining heat where necessary. 

We designed a two-stage heating system: 1) In the spring and fall, the radiant floor provides enough heating to maintain space temperature while the fan coils were in cooling mode, and 2) in the winter the radiant floor kicks the first stage of heating.

Ventilation: There was a crucial fresh airflow gap in the penthouse HVAC system.

Problem: Due to space constraints, the penthouse had fan coils that served multiple zones with modulating dampers, which operated on modulation based upon duct static pressure.  Fresh air to the spaces in the home was not planned in the original mechanical system. 

DMA Solution: We designed a dedicated outside air system using Energy Recovery Ventilators (ERVs) to integrate with the existing total 5-story building automation system intended to include the penthouse mechanical system control strategy.   We optimized the make-up air system design with the ERV system to maintain the proper building pressurization for the two 1200 cfm range hoods and activated a very detailed control sequence of operations. End result:  The multiple systems are now synchronized and work together seamlessly to have a complete airflow and ventilation system for the penthouse.  

Temperature Control: Owners were uncomfortable with changing and out-of-control interior temperatures

Problem:  The owners were frustrated by the changing temperatures in their home and were confused about the cause of the problem. They knew the mechanical system had the correct capacity to cool the space well below setpoint during 100-degree days and could heat well above setpoint on zero-degree days. This was demonstrated during construction while the final woodwork was being finished.  The space just could not maintain the temperature set point.

DMA Solution:   After several meetings with the installing contractor and controls contractor ownership, they decided to engage DMA Engineering to do commissioning of the space.  This is when the magic started happening.  It quickly became apparent the mechanical system was not ready to be put into full service.  We found:

• Valves that were manually closed
• Fan coils with the wrong control boards
• Malfunctions in the radiant floor system control valves
• An unfinished sequence of operations on the building automation system (BAS)
• …and even a fictitious balance report, and a sequence of operations not finalized on the BAS.

After several site visits and careful reviews of the BAS operation, we created detailed deficiency reports that led to a full rebalance and a comprehensive evaluation of the sequence of operations programmed in the BAS. Finally, the spaces in their penthouse were able to maintain the comfortable setpoints that the owners desired.  The design intent was realized through commissioning that drove the deficiencies to resolution resulting in meeting the client expectations.

The moral of the story: Involve us early and often.

We at DMA pride ourselves on providing designs that work – for people and their environment. Our Luxury Residential engineering services include commissioning in every engagement.  Often, commissioning is the key to make sure that our buildings – whether commercial or residential – work as intended. Not just DMA designs, but all designs.