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Home My WebLink About20180720 - BOD_UpdatedDraft Basis of Design Document BOD for Public Works Facility-phase I Page 1 of 3 IOWA CITY PUBLIC WORKS VEHICLE STORAGE BUILDING IOWA CITY, IOWA BASIS OF DESIGN DOCUMENT MAY 29TH, 2018 The Public works Vehicle Storage building can be broken into two distinct areas: Vehicle Storage: Large open parking area and mezzanine area. Shop Spaces: West of Grid 3 and below mezzanine MECHANICAL SYSTEMS SHOP AREAS: The shop areas are served by a nominal 25 ton air-cooled variable refrigerant flow system (DAIKIN). The air-cooled condensing units are located on the mezzanine level within the building and reject their heat to the open vehicle storage area. The indoor units served by the condensing units are a mix of ducted fan-coils and ceiling mount exposed cassettes. The system shall be capable of “heat recovery” allowing the various fan coil units to simultaneously heat and cool independent of each other. The ventilation air to the shop spaces is provided through a 5,400 CFM energy recovery ventilator unit (DOAS) utilizing a total heat recovery wheel, natural gas heat, and direct expansion cooling. The wheel specified in the DOAS unit is an enthalpy total energy recovery type. The DOAS has the capability of recirculating air during unoccupied times to provide dehumidification. Back-up heat is provided for the fan coils via high efficiency condensing gas fired unit heaters located at the exterior wall near doorways and air intake louvers. The various shop areas with overhead doors have the possibility for a truck to pull in and park for a short amount of time. Due to this fact individual gas detection sensors (NO2 and CO) and control panels are provided in each room. these are interlocked to individual 1,900 CFM purge exhaust fans and wall mounted intake dampers to pull clean air through the space. VEHICLE STORAGE, WASH BAYS, AND MEZZANINE HVAC: The vehicle storage, wash bays and mezzanine areas are heated only spaces. Gas-fired radiant tube heaters (Roberts Gordon) will provide heating to the vehicle storage area as well as the wash bays. Condensing gas fired unit heaters will heat the mezzanine area. The code required constant ventilation airflow is to be provided by the same Energy Recovery Ventilator serving the shop areas. The vehicle storage area will contain a gas detection system (CO and NO2) throughout, spaced with a 50ft radius to provide full sensing coverage. This system will enable a “purge event” to evacuate excess gas levels from the space by increased exhaust airflow pulling across the space. Upon signal from the gas detection system 4 12,000 CFM exhaust fans will engage and pull air from east to west flushing the space with fresh air. A large 50,000 CFM gas fired make-up air unit will be interlocked with the gas detection system and exhaust fans to deliver makeup air to the vehicle storage area and to heat the incoming air in the winter. Draft 07/2 0/ 2 0 1 8 1 2: 0 0: 2 1 P M Page 2 of 3 Along with radiant tube heaters, and exhaust fans, destratification fans (count 40) are provided throughout the vehicle storage and wash bay areas to assist in evenly mixing the air in the space as well as quickly drying the floors. TELECOM ROOM AND ELECTRICAL ROOM HVAC: The main telecom room, north and south electrical rooms as well as the elevator equipment room will be served by VRF indoor units tied to the central VRF system serving the shops. Each room will have independent thermostats. The condensing unit will be placed in the mezzanine storage area to allow for cooling all year long. Controls: Each of the individual shops will have one or more dedicated fan coils providing temperature set point control to the occupants. These will be controlled through the manufacturer specific control system. The building will have a light facilities management system (FMS) throughout, the basis of design for controls is Baker group controls utilizing their niagra system. This system will interface with the various equipment and allow inputs and monitoring of the systems from a web based portal. The roof mounted DOAS unit and gas fire makeup air unit will be primarily operated by their internal factory controls systems. REASONS FOR SYSTEM SELECTION A. The selected HVAC systems throughout the building are being considered primarily to provide the most cost effective and energy efficient solution. The VRF system utilizes refrigerant to transfer energy between zones and provide heat recovery, in addition to this the DOAS unit will be exchanging heat between the exhaust and outside air intake airstreams. Overhead gas fired Radiant tube heaters provide outstanding comfort in heating only spaces especially high ceiling areas. Water heating: There are two electric tank type water heaters on the project serving the various showers, lavatories, and other fixtures in the building. These water heaters will be provided with recirculation piping and associated pumps. LIGHTING SYSTEMS The building’s lighting system consists of state of the art LED fixtures, utilizing high bay, high CRI type fixtures. The building light fixtures will utilize only LED sources with 90+ CRI for interior and 80+ CRI and bug ratings for exterior lighting. Lighting power density will be kept to a minimum to assist in keeping building energy usage down. At the same time, light levels will be appropriate for working and providing a safe facility. Smaller spaces (i.e. offices, small restrooms, storage) will be controlled by standalone dimming occupancy vacancy sensors. Overrides will be provided in these spaces where the lights have to be turned ‘on’ and ‘off’. Large spaces (i.e. workshops, Wash bay, parking) shall be controlled by lighting controls panels for time-of-day operation, day light dimming, and occupancy sensors. Overrides will be provided in spaces where the lights may want to be turned ‘on’ or ‘off’ at alternate hours. Daylighting sensors will be installed in all spaces to utilize more day lighting due to large windows, sky lights, and natural day lighting area to bring the lights to the appropriate lower-level when sunlight is sufficient. The exterior building and parking lot lighting fixtures shall be controlled by time-of-day and/or photocell. Fixtures will also be cut off and bug rated type. Page 3 of 3 A future plan to install photovoltaic solar panels to generate energy is set into place and designing measures are being accounted. Lighting connected to lighting control panels and/or on-off photocells shall have the ability to be controlled by the building Facility Management System (FMS). The building will have occupancy sensor-controlled task lighting and occupancy sensor controlled electrical receptacles to keep the electrical consumption to a minimum. Measurement and verification load will also provide assistance in administrating each load type and keep the consumption reasonably low. A. Fixture type(s) – LED fixtures with high CRI B. Lamp and ballast type – Interior fixtures with 90+ CRI and exterior fixtures with 80+ CRI C. Control type- Automatic controls for occupancy, day light controls and time of day controls. REASONS FOR SYSTEM SELECTION B. The selected lighting system and fixtures types are being considered primarily due to high performance, low wattage usage and cost effective. The efficiency of the fixtures is very high and provides a visual comfort to users. High CRI also helps to provide a fixture with high lumen output and high temperature ratings. DESIGN ASSUMPTIONS The mechanical and electrical systems for this project were design to meet industry standards and general good practice, including, but not limited to: · ASHRAE Standard 90.1-2013 · ASHRAE Standard 62.1-2013 · MODUS company standards · LEEDTM Green Building Energy Efficiency Goals TABLE 1 DESIGN PROPERTY HEATING COOLING OUTSIDE AIR DRYBULB TEMP -10 °F 95 °F COINCIDENT OUTSIDE WETBULB TEMPERATURE -10 °F 76 °F REGULARLY OCCUPIED SHOP SPACES INSIDE TEMP 70 °F +/- 2° 74 ° +/- 3° TELECOM AND ELECTRICAL ROOMS 60 °F +/- 2° 75 ° +/- 3° VEHICLE STORAGE AND MEZZANINE 50ºF +/-2º N/A DESIGN RELATIVE HUMIDITY 40% N/A TABLE 2 BUILDING CONSTRUCTION ENVELOPE CONSTRUCTION U-VALUE (BTU/H/FTS/°F) SHGC WALLS 0.12 - ROOF 0.066 - WINDOWS 0.45 0.48 SKYLIGHTS 0.38 0.38 0.420.74 0.42 0.33