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     In the city of Denver, buildings and homes are responsible for 63% of greenhouse gas emissions. These places are where we spend the majority of the day working and living are the key to having a successfully sustainable environment, and city. The city of Denver is looking to reduce greenhouse gas emissions completely by 2030. Making redevelopment a priority will reduce the levels of emissions throughout the city, especially in an urban city.

 

     To begin this process, the City of Denver needs to expand on their pre-existing programs that are in place to incentivize building owners to redevelop their buildings to meet new standards. The Green Buildings Ordinance Energy Program is a great initiative that requires buildings over 25,000 square feet to install a cool roof when they replace their existing roof. The program includes sustainable redevelopment tools, efficiency standards, and improvement projects that aid building owners in starting a redevelopment project.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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     For the city of Denver to move forward even further and faster than their current rate, there needs to be a set of rules to push building owners to move towards sustainable redevelopment. Tax exemptions for redeveloped projects, new zoning for commercial space, and an expedited process of receiving a building permit are crucial to helping Denver’s commercial properties move in the right direction. 

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Rating Systems 

     There are a number of organizations that assist and evaluate the redevelopment process for commercial space such as LEED. Their rating system is based on the sustainability within the building to support the environment while remaining a successful business operation. LEED has the ability to partner with the city of Denver to promote new projects, as well as incentivize old buildings to reshape their existing foundation into a new and improved sustainable foundation to reduce emissions. 

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Net Zero Buildings

     Net Zero buildings are an essential part of creating a sustainable work environment. These net zero buildings boast energy consumption nearly equal to their energy output. The goals of these buildings are to reduce water consumption, carbon dioxide emissions, and waste reduction. Building owners can cut down on emissions and energy use with distributed energy systems (DES), which control sensors and meters that monitor the performance of the building’s use of light, heat, and cooling. The use of DES will reduce the overall operation costs, energy reliability, as well as improve revenue. 

 

Construction

     Sustainable redevelopment in commercial buildings is rapidly becoming a strong and healthy business in the construction industry after recognizing many negative environmental issues, and potential social and economical benefits. In a green building, all stakeholders including an architect, a contractor, engineers need to collaborate to successfully complete integrated green design and construction that can eventually achieve the goals of sustainability in construction. Since there are many negative environmental issues and problems as well as many opportunities, it is very important to develop an Integrated Construction Process (ICP)  that can help all stakeholders to successfully implement green building strategies and technologies at the construction phase of the project development.

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Next Steps For Sustainable Water Solutions 

     Although Denver only sees around 15 inches of precipitation each year, it can come to be an important asset in creating a sustainable water future in Denver. Rainwater capture can only be done on a small current in Denver, but it can play a major factor in helping reduce building water waste. Rainwater can be captured by certain rooftops, parking garages, and pavement near the building. If the rainwater can be captured and filtered it will help the building long term.

 

     Onsite wastewater recycling system (WRS) is something that is new to Denver, and Denver Water is the first office building to create it, on their new campus. The WRS functions by collecting all the building's wastewater and cleaning it through a series of mechanical and natural processes. The WRS is designed to treat up to 7,000 gallons a day of office wastewater. The wastewater can flow from an office building to an underground multi-stage treatment unit.

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Onsite Wastewater Recycling System 

     Onsite wastewater recycling systems are used to treat wastewater for both residential and commercial properties, onsite water goes down into large tanks underground and treats the water, then returns the treated wastewater back into the received environment. 

The water from commercial buildings is entered into the recycling plant where it is treated with a biologically aerated filter process, which helps remove ammonia. Air is then injected into the base of each treatment cell and the aerated water flows through individual treatment cells containing styrene-based media. The media provides a high specific surface area where micro-organisms attach and act as a filter media for suspended solids removal. This treatment process helps minimize the number of chemicals needed downstream and keeps salt levels low in the treated water. After this, the water is rapidly mixed with sticky coagulants that can capture suspended solids and nutrients.

      The water is then stirred with large, slow-moving paddle wheels. This creates turbulence and increases the contact of solid and coagulants. This allows for particles to grow and get heavier. The heavy particles will then settle out in the sedimentation basin within the tank. The water then passes through the filter beds containing a type of coal called anthracite, which helps trap the remaining solids. After filtration, the water passes into contact basins where chemicals are added for disinfection and corrosion control before distribution to customers. (denverwater.org)

      This system will allow for buildings to be able to use the wastewater that they produce in order to help reduce the amount of waste that leaves the facility. Overall, we feel that this is a great step for helping Denver buildings become more efficient in their water use. 

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Rain Water Collection 

     Denver receives about 15 inches of precipitation every year, which, compared to other major cities, is quite low. Due to Denver’s dry climate and lack of rain, water conservation has always been a priority. Commercial property buildings take up a major part of Denver’s square footage throughout the city. Thus, we believe incorporating a water collection system on all buildings could help with Denver’s water issues while conserving water and helping the environment at the same time. Rain harvesting became legal in Colorado in 2016, but that was mainly for residential single-family homes or attached multi-family homes with four or fewer units from rooftops. The law allows up to two rain barrels with a combined storage capacity of 110 gallons. Although this helps residents, there needs to be a law that allows for commercial buildings to collect water. 

     In 1922, Denver created laws on the water that are still in place to this day. The law passed was “first in time, first in right.” Meaning people who were first to file for water rights obtained senior rights. In order for our solution to be effective, water laws in Denver would need to change and allow water collection from commercial building owners. This process is called rooftop harvesting. Approximately 550 gallons of rainwater can be collected for every 1000 square feet of collection surface per inch of rain. Denver Water's new complex will use a rainwater collection method on the roof, covering around 82,000sqft for collection. Denver Waters's new complex sets new boundaries for sustainability with its innovativeness. If buildings could create a collection process and system for rainwater,  they could easily have enough water to power their buildings and more. This would help increase sustainability in Denver and decrease operating costs for building owners. 

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Efficient Fixtures In Office Buildings

     Another approach that we think will help make a major difference in creating a sustainable solution for water use in commercial buildings is the fixtures. Some might think that this is obvious, but if a building does not have efficient fixtures, such as toilets and sinks, then there can be a lot of wastewater that is consumed in the building.

     Toilets use a significant amount of the total water demand in office buildings. An average toilet uses around 6/L per flush. If office buildings can start to move towards vacuum toilets, which is a toilet that uses suction for the removal of feces and urine, using a vacuum type system to drain the toilet, leading to an onsite wastewater treatment plan that we have discussed above, then the water can be treated. The average flush of a vacuum toilet uses 1-1.5/L per flush. 

     The next type of water system that can be used is more efficient taps in office buildings. Adjusting the flow rate of taps while maintaining spray pattern through the installation of the flow regulating tap aerators can help significantly reduce rap water use in-band basins and kitchen sinks. A typical flow rate for a non-efficient tap is usually 10-12L/minute, compared to using an adjusted tap flow can reduce to 2.5L/minute.

     These are a couple of ways that we believe office buildings can change out fixtures in order to make water use more sustainable in pre-existing office buildings. Although the upfront cost is more for these types of materials, in the long run, it can help save the building owners/tenants more money, while reducing their impact on the overall water usage, which will help achieve the ultimate goal. 

(This content was helped received by Reseachgate.net)

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