For example, I've seen where a hobbyist investor/developer works on project, they hire an engineer and/or architect, but they ended up missing something vital, i.e. drainage issues, environmental, fire dept review, planning the wrong type of product for that market (buyer & renter demographic), etc.

The architect and I have been thinking the exact same thing, with all the people looking to build/ live in this area we could sell just about anything under 500k instantly.

definitely want to speak to an engineer and architect 

They are both architects, they have good credit, they are solid buyers. 

That means generally the only people truly qualified to do cost segregation are construction engineers or architects who have been trained in cost segregation and the pertinent tax code.

I'd be specific as to what 'ecofriendly' means to you when talking with GCs and Architects...

Scope of Work:Initial Assessment: Our team conducts a thorough assessment of the property to evaluate its current condition, identify structural issues, and determine the scope of renovation required.Design Concept: Collaborating with architects and designers, we develop a design concept that blends contemporary elements with the historic character of the row house, maximizing space utilization and optimizing layout efficiency.Structural Repairs: Structural repairs and reinforcements are undertaken to ensure the integrity and stability of the building, addressing any foundation issues, roof leaks, or structural deficiencies.Interior Renovation: The interior of the row house is completely renovated, including the removal of non-load-bearing walls to create open-concept living spaces, installation of new flooring, upgrading electrical and plumbing systems, and installing energy-efficient fixtures and appliances.Kitchen and Bath Remodeling: The kitchen and bathrooms are transformed with modern finishes, custom cabinetry, quartz countertops, and high-end appliances, creating functional and stylish spaces for daily living and entertaining.Historic Preservation: Special care is taken to preserve and restore original architectural features such as exposed brick walls, decorative moldings, and hardwood floors, enhancing the property's historic charm and character.Exterior Enhancements: The exterior of the row house receives a facelift with fresh paint, repaired masonry, restored windows, and landscaping improvements, enhancing curb appeal and contributing to the overall aesthetic appeal of the neighborhood.Quality Assurance: Throughout the renovation process, our team adheres to strict quality control measures and standards, ensuring that workmanship meets or exceeds industry best practices and building codes.Finishing Touches: The finishing touches, including interior decor, lighting fixtures, and hardware, are carefully selected to complement the design aesthetic and create a cohesive and inviting atmosphere.Timeline and Budget:The single-family flip project in the Philadelphia row house is estimated to be completed within [timeline], with a budget of [budget].

Also looking for trusted general contractors and architects in the area. 

@Roger Verastegui as an architect turned contractor, traditional construction is a more affordable way to build that pre-fab.

Also, engage either an architect or civil engineer, or both.