Commercial HVAC System Review

We recently purchased a vacant office building (60,000 SF, 4 floors of 15,000 SF), and the HVAC system needs a complete rehaul. I am looking for a mechanical engineer to confirm our thinking (gut check), inform us if we should go a completely new direction, and/or if there are any other tweaks we may consider that would have utility savings, etc. Please see specs and notes below. Phase 1 We will start HVAC upgrades with floors 3 & 4. The floorplan will state the same so we are only replacing HVAC components. After completion of these floors, we will proceed with the other floors depending tenant requirements. Heat pumps Approximately 20 per floor, 80 total Condition - needs replaced Upgrade Heat Pumps – we are replacing with same specs (3 ton, same electric, etc.) with current model, model number 50PCH036ZCC6ECC1, Carrier. cooling tower installed March 2013, assuming works boiler Rite Boiler model number: 325 serial number: 701-3628 3,250,000 BTU condition – needs replacement Upgrade - retubing and refracturing. heat exchange, quantity two condition – good, assuming works air handler condition – assuming operable, don’t believe will need to replace. RTU on roof One Rooftop - It feeds southeast wing of 4th floor, assuming we will reconfigure for heat pumps. Exhaust fans On fourth floor mechanical, assuming works. Water Supply/Return Lines Shot, replacing with all copper. Controls Controlled by an Automated Logic Control System, computer parts were stolen. Do you have a recommendation for a replacement control system (multiple options) that we may be able to consider, including sources to buy such used and/or new. We are considering not putting in new control system and using thermostats only – pros/cons/gut check. Attachment 1 – floorplans that note locations of heat pumps Attachment 2 – the adjacent property did some HVAC work and I attached their permitted drawings as a reference. The buildings and HVAC systems are very similar so you can make assumptions that the components in this building are identical to ours. Attachment 3 – HVAC contractor review of specs of HVAC at property. Questions I will want you to answer to get the job. A summary of your experience with this type of project and your qualifications. Answers should include your experience with multi-story office buildings, centralized boiler/chiller systems, etc. If you are based overseas, confirm that systems in your market are similar to systems in US Market. Questions we will want you to address if we hire your for this job. Is replacement of the components referenced above the best solution, assuming similar uses? If so, why? If not, why? What are the efficiency gains if we replace these with new. For example, if the heat pumps are from 1980 and we are replacing them with 2022 models, how much more efficient are the new heat pump? Are there any other items we may want to consider that would be more efficient, specifically saving on utility consumption? Is a control system necessary or are thermostats just as efficient? If so, why. If not, why. If we want to replace the controls, what are our options for replacement systems? Are there used options as opposed to new. Can we consider other brand alternatives? Can you provide us with pricing of such options that we can expect if we purchase direct, provide us with direct source and quote. The heat pumps that are being replaced are approximately $3,000 per pump. Is this best heat pump? Alternatives? If so, why? What other questions should I be asking? Note: the property is located in the state of Colorado so the winters can be cool, the system has to address climate appropriately.