Greening Your Building: Installation Part 1

Once you have planned out your space and schedule, it is time to finally start the installation of your green building project. At this point, it will feel like you have already accomplished a lot without anyone picking up a shovel. But it isn't over yet, now it's time to make sure installation goes smoothly and unnecessary crises can be averted. In this article, we will go over the importance of testing and best practices for installing a green roof system.


Thorough testing of all materials, technology, and components in the early stages of installation will be critical to avoiding mishaps or do-overs. For example, testing out your solar panels power output on the ground before installing them on the roof will help you foresee any issues or possible manufacturer defects. If you are installing a green roof, testing for leaks in the waterproofing membrane or drainage system before installing the growing medium can also help you detect early problems. You will also need to make sure any products or materials are tested and warrantied in your specific climate and microclimate.

Testing also helps you determine if the issues are product related or installation related. Once you are done with initial testing and have installed the components you need, continual testing should be done in order to determine if the products are working according to the manufacturer's' standards over a longer period of time. For example, is the renewable energy technology you have installed performing at its best? Is the plant growing medium on your green roof absorbing and retaining enough water?

Best Practices for Installing Green Roofs

First and foremost, you will want to review the design of the green roof system carefully and ensure proper transportation of the materials to the construction site. Hiring green roof specialists will help ensure that the materials are well taken care of during the installation process. Make sure you have a quality assurance program set in place before you begin. We will be touching on best practices for quality assurance in our next article.

One of the most important elements of a green roof system is probably the waterproofing membrane. Carefully inspect the membrane and continually check for damage throughout construction. Testing for leaks on a regular basis will be essential, especially if the membrane is left exposed during installation. Ensure other trades do not puncture holes above or below the membrane.

In addition to waterproofing, irrigation is essential to the success and longevity of green roof systems. You will need to carefully coordinate with other utilities and subcontractors while implementing your irrigation system. More often than not, irrigation will need to be installed by a certified applicator in order to keep the warranty valid. Double check to make sure the design and layout of the irrigation will make future maintenance easy and accessible. And as with the waterproofing membrane, check for damage and defects often.

Of course, we cannot forget about what makes the green roof a green roof: plants. Although you can't really "test" plants, you can keep tabs on your sources and continually check the quality of the vegetation. Inspect the plants at the nursery before transportation and then after they arrive on site. Reject any plants that are dying or have disease, and remove any weeds. If the plants arrive before the irrigation system has been installed, arrange the plants as they will be planted and use supplemental watering to keep them healthy until installers are ready. This is a good opportunity to check with your design team to make sure the arrangement of the plants is appropriate for long-term health.

Although you can't plan for everything, and something may undoubtedly go wrong, proper testing can reduce your stress and make sure that your project components are working properly, the project is easy to maintain long-term, and that it lasts as long as possible before needing any upgrades or retrofits.

Greening Your Building: Pre-Installation

Before installation of your green building project begins, you’ll need to prepare with some pre-installation planning. In this article we will cover everything that needs to be planned out before you break ground: Site and material preparations, conveyance methods, staging, and scheduling.

Site and Material Prep

For projects in existing buildings, site preparation will take much more time and effort that simply working from the ground up. It is important that contractors coordinate with existing facilities operations in the early planning stages and communicate properly any needs or issues that may arise. Generally speaking, it is best that a liaison from the general contractor's team work directly with building operations, as well as surrounding neighbors, to ensure the construction goes smoothly.

Sourcing and preparing materials, especially for green building projects, can be a uniquely challenging task. Since origin and performance standards for green building materials often play a role in the overall sustainability of a project, finding the appropriate materials that meet those standards within your local region can at time be challenging. In the initial design phase, designers will select and choose the appropriate materials for the job. It is important that the owner and/or contractor doesn’t employ “value engineering,” which is to replace the selected materials with a cheaper alternative. If budget concerns arise, working with your designer to select appropriate alternatives that are more economical will generate better results.

Conveyance Methods

Especially the case with green roofs, solar arrays, and tall buildings, it is important to choose the appropriate conveyance methods to get your materials in otherwise hard to transport places. In other words, how will you get all your construction materials to the appropriate spot? Working with the various trades to understand the materials and the best way to handle them is important, but keep in mind your staging area may be limited, as well as any local ordinance limitations. Whether it be a forklift or a large crane, careful handling of vegetation and renewable energy technology is your greatest concern.

Staging and Scheduling

Staging involves properly coordinating how materials will be delivered, and where materials will be stored on site. This involved careful consideration, because you will need to ensure that you have enough workers to handle what materials exist on site, while also ensure you have enough materials to keep your workers working. It is an important balance that may need some tweaking during construction. Many of your subcontractors will handle staging to a certain extent, but you may be required to provide them with the space they need. If your project is in an urban area, staging locations may be limited.

Just as ensuring you have enough room and are using space wisely, you must also ensure that you have enough labor and are using timing wisely. Scheduling the shipping of materials, stages of materials, labor force, and coordinating among various trades will be essential to the efficiency and timeline of the project.

Make sure you have all the planning documents accessible to everyone involved. Usually the general contractor will communicate to the subcontractors during the scheduling process. As we discussed in the previous article, pre-training can facilitate understanding of the scheduling and staging process, as well as create channels of accountability if the project goes off-schedule. Hiring an expert in green building practices can help you facilitate everything that goes into your green building project. For more information, contact Sow Green today and we can help you break ground on your next green building project!

Greening Your Building: Awarding Contracts and Pre-Training

Once you have successfully received all of your bids for your green building project, you are now ready to select a contractor and begin pre-training.

Evaluating Bids

Going through all of your bids, depending on what format your bidding invitation takes, can be a daunting task. Like going through a pile of resumes during a hiring process, many of them will not stand out or even meet the basic specifications that you require.

If you have the staff to do so, having someone else (or Sow Green) vet out the top 10-20 bid proposals for you can help you save time and effort. If not, you can vet them out quickly yourself by going through and removing any that clearly to not understand the specifications you have outlines, or any that may have excluded important aspects of the work that you may or may not have outlined. Creating a simple checklist beforehand might help you review your bids faster:

  1. Are the project specifications understood?

  2. Has the bidder included the most important elements of the work described?

  3. Have they added references and past work?

  4. Have they listed available manpower and equipment?

  5. Does the schedule of values align with your goals?

If any of the answer to these questions is “no” you may want to exclude them from the beginning. Going in this order will ensure that you don’t waste time evaluating documents in the bid if the most basic needs aren’t met. Once you’ve weeded out a “Top 10” list, review the remaining groups references and past work, and thoroughly review the schedule of values. Once you've done that, you should only have a few options left. At that point only you can decide which contractor is right for your project. Once you’ve made a selection, it is time to ward the bid and start your pre-training so that your project can move forward!

Construction Pre-Training

When initiating a green building project, pre-training is becoming increasingly important. Pre-training is a series of meetings and presentations where all of the contractors, including any sub-contractors (such is renewable energy installers, landscaping contractors, roofing contractors, etc.) attend in order to ensure each one understands the scope of the others work.

Green building projects tend to use more subcontractors in specialized trades, and often without pre-training they can inadvertently step on each others toes. While communication is key, understanding what each contractor is doing and their timelines creates better understanding so that potential oversight, accountability, and conflict resolution takes place. It is also the time to establish channels of communication for problem solving, as well as developing a safety plan.

These meetings do not have to be long or complicated, as specific details among contractors can be organized via e-mail or video conferencing. We recommend that at least one or two of the meetings are in-person, so that everyone can meet face-to-face and establish a strong partnership from the start.

Many time issues arise simply because each contractor doesn’t have a holistic picture of the entire process, and instead only focuses on their part of the project. They also aren't aware of who is in charge of what, so bad communication channels are created. Although pre-training takes more time and effort, the amount of time and effort it saves is worth it in the long-run, as well as the reduction in stress on the project manager or owner.

Need help in managing all those contractors? Sow Green is here to help you manage your green building project. Contact us today for a free consultation and discover the Sow Green difference!

Greening Your Building: Contract Bidding and Negotiating

The third in our Greening Your Building article series, we go over how to navigate the bidding process to find a contractor. First we will explain the various project delivery methods. Then we will discuss the different types of bidding and best practices. If you don’t think you need to initiate a bidding invitation, you might find a contractor you trust and simply negotiate.

Project Methods

There are four ways to deliver a project, and depending on your budget and the complexity of the project scope, you might prefer one or the other.

Design-Bid-Build: Most traditional method of handling construction projects. The architect or designer are hired independently of the contractor that handles the construction.

Construction Management at Risk: Like the Design-Bid-Build method where the contractor and the architect are hired separately, but the contractor starts working on the project before the design phase begins. They can even at times help choose the architect.

Design-Build: An increasingly popular method in which the design and construction of the project are handled by the same contractor, and both phases are included in the price of the completed project. This method can often offer the best value and expedite the building timeline.

Integrated Project Delivery: A system where the architect, contractor, and owner are set up as a team that shares the risks equally, usually with a legally binding contract. It is the newest method of delivery, and is probably the most efficient at reducing problems and issues.

Different Methods of Bidding

How much time you have, or how complex your project is, will determine which method of bidding you want to pursue. There are several options for selecting a bid, and many owners use secure online bidding sites to find the best contractor. Here are a few methods that are commonly used to select construction bids:

Pre-Qualified Bidding: This is most common for green building projects since owners often seek those with green building certifications or past experience. The selection pool is smaller and easier to manage, but also limited by market fluctuations and less competition.  

Competitive Bidding: When bidding is open to all contractors. The selection pool is much larger and therefore has more competitive bid options. It can take much longer, and doesn’t always offer the best value.

Design-Build Bidding: This is when the design firm makes a bid on the project before the design phase even starts. This gives a more accurate timeline and the owner has more control over the cost of the project.

Bidding Best Practices

Have realistic expectations: Communication is key in establishing realistic expectations about the budget and timeline of the project. If you want the project to be finished quickly, expect things to get expensive. In the same way understand that if you are getting a great deal on price the project timeline might move much slower than you would prefer.

Clarity the details in the design phase: Having well defined designs and objectives to offer contractors that are bidding will help them give you a more accurate representation of what they can offer you, and at what price.

Understand the scope and project requirements: This is ultimately why many projects are bringing the contractor into the fold as early as the design phase. The better the contractor understands the scope of the project from the earliest stages, the faster they can get to work and deliver on time.

Assess contractor qualifications thoroughly: Everything from the size of their staff to the certifications they hold will help you determine whether or not they can handle the project as promised. Get recommendations and interview past clients before offering the job.


Sometimes the owner may already have a working relationship with a contractor and will instead enter into negotiations for a project. This work if the contractor(s) have specialized skills or experience working on similar projects in the past. For example, if a landscaping contractor that have installed successful green roof projects in your local climate, you might simply negotiate with them to manage your green roof instead of taking the time an effort to issue an invitation to bid. This can save time but you don’t always get the best price and it can backfire if contracts are not thorough in protecting both parties throughout the project.

Selecting a contractor can be a stressful and intensive process, but luckily there are many best practices in reviewing and selecting a contractor you can trust to get the job done. Need help in overseeing and selecting your green building project contractors? Sow Green can oversee that for you, just contact us and we can offer a free consultation.


Greening Your Building: Design Phase

After completing the Pre-Design Phase, you are now ready to move on to the Design Phase. The Design Phase is where you will determine how the project will be constructed and maintained. There are some key considerations to make during this time, and we’ve outlined some important ones here.


How your project will reach it goals and whether or not it will comply with local ordinances will require a lot of research. If you are designing a new building or upgrading an older one, you may be required to install a green roof, or you might not. For example, the City of Denver is proposing a requirement for cool roofs on all buildings exceeding 25,000 square feet. Other options for compliance will exist, such as ground level green spaces, solar arrays, and partial green roofs (you can read the proposal here). Understanding your local laws and requirements first and basing your design off of them will help you avoid last minute changes or unexpected fines.

It is also recommended to do research on how your building might exceed the local and state requirements, in order to achieve a higher standard of sustainability and potentially attain special certifications, such as LEED. How can you go the extra mile with your green building project while staying within your budget and achieving your goals? The answer requires a lot of research, but it is worth it!


There are many financial options for sustainable and green buildings, whether it be new construction or upgrades. Green roofs or permeable parking lots can get you fee reductions for stormwater management, since they help alleviate the pressures of stormwater runoff. Low interest financing options, such a C-PACE, can get your energy efficient project off the ground with very competitive rates and a 20-year payback. This option is very attractive, since many green building projects, such as green roofs, can give you ROI in less than 10 years. Regardless of which options you choose, establishing a budget and discovering ways to maximize it will be essential to the design phase.

Site Analysis

Project design parameters will ultimately depend on the site and space your project will inhabit. Doing a thorough site analysis will help you understanding your limitations as well as bring opportunities to light. If the project includes a green roof or renewable energy, a climate evaluation for sunlight, wind shade, precipitation rates, and possible microclimates will be necessary for choosing the vegetation or technology that is most efficient and easiest to maintain.

Since many green building projects often utilize green roofs and other green spaces, understanding the vegetation needs, access to water and site accessibility for regular maintenance will need to be considered during the design phase. If you are greening an existing building, understanding the sites current systems, such as HVAC, stormwater drain, and energy use, will help you better understand ways to implement the project while taking advantage of these systems.

Cost/Benefit Analysis

We know buildings often cost money, but some buildings can save or even make money. Green building projects often cost more initially than traditional building materials and technologies. But green buildings offer a better return on investment per dollar due to their ability to conserve resources that will only get more costly as time passes (such as energy and water). When designing the project, look at the cost/benefit for all the options that are available to you, so that you can make a well informed decision about what to implement.

Everything established during the design phase will be difficult to undo later, especially if incentive programs are involved, so it is important to consider all decisions carefully during this time, and include as many stakeholders into the conversation as possible. Need help in designing and implementing your green building project? Sow Green has over 10 years of experience, and would love to help you get your project off the ground.

Greening you Building: Pre-Design Phase

This is the first in a series of articles on everything you need to know about implementing a green roof or other green building elements into your building project. Before you can even start designing your green building, there are a lot of considerations to be made first. We call this the Pre-Design Phase, and it is probably the most important step in the process.

Determine the Goals of the Project

What are the main goals you would like your project to achieve? For example, is it food production, energy conservation, or simply complying with local ordinances at the lowest cost? You may even have more than one goal in mind if you are attempting to reach a certain level of certification, such as LEED. Regardless of what they may be, establishing your goals first will help you stay focused on achieving the optimal design for the roof.

Rethink the Design Hierarchy

Integrative and environmental design projects often require a more holistic and integrated team hierarchy than traditional building projects where the architect oversees the various people involved. Instead they often need a more multidisciplinary approach in order to achieve their goals (such as conserve energy, manage water quality, support biodiversity, promote healthy environments for people, etc.). With all the stakeholders involved in the design process, you can gain valuable insights that allow the project to move smoothly and succeed.

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Determine the Scope and Scale of the Project

Once you’ve set your goals, you’ll need to understand your site’s constraints and opportunities to establish a baseline for success. If you decide on green roofs, they should at the very least ensure leak-free waterproofing, health plants, and assume structural integrity. Beyond that, a structural engineer can help you do things such as a preliminary code analysis, structural feasibility investigation, and basic concept designs.

Setting a budget is also important in determining the scale and scope of the project. Green roofs can cost anywhere from $10-25/sq ft to install, but the payback on the average green roof project is around 6 years if well designed and maintained. Solar and LEED certification also have higher upfront costs, but provide energy savings and increased valuation. Luckily there are many financing options available that allow green project to be added to new and existing buildings with little to no upfront cost.

Consider Performance Specifications

Using an expert to advise on performance specifications for the project can help contractors choose materials and meet various project certification requirements. They also aid in meeting local ordinances and the end users needs and expectations.

Determine Your Maintenance Needs

It may seem like putting the cart before the horse, but at best a green roof, solar or green certification projects should come with at least a 5-year maintenance plan. Considering the level of maintenance needed, this is best done at the beginning moving into the design phase.

There are many things to consider before even going to the drawing board, but there are many benefits to installing a green roof, solar or green certifications. You take advantage of these benefits without worrying about all the moving pieces throughout the project timeline with Sow Green. Contact Sow Green today and let us help you with your green building project.

What the changes to Denver Green Roof Initiative means for developers

By Alyse Opatowski and Harlan Blynn

Featured In CREJ’s June 20-July 4, 2018, issue

In November, Denver voters passed the Green Roof Initiative that requires buildings with more than 25,000 square feet to have a green roof or solar panels. Since January, varied stakeholders comprising the Green Roof Task Force Committee have been meeting to propose changes. They will then make a recommendation to City Council, who can make changes with a two-thirds vote (nine council members), starting at the end of this month.

While many developers opposed a green roof mandate, there are benefits to green roofs, and the new proposed initiative offers a lot more options. We break down how the new proposal can help and hurt developers versus the original ordinance.

How the New Proposal Helps Developers

More options. New construction would have eight options to choose from under the ordinance, instead of the initial two proposed. With these options, buildings can have LEED or Enterprise Green Communities certification, energy-efficiency programs or off-site solar. This allows more flexibility for developers. Many of the options don’t take up additional space, and we all know how valuable each square foot is in Denver’s economy. According to the committee’s cost analysis, the cost increase resulting from these options is lower than the initial proposal. However, their calculations only look at energy savings and do not take into account myriad benefits green roofs can offer.

Aids affordable housing projects. At one point, they were going to exclude affordable housing projects. As of now, they are not exempt. While this may be more costly up front, it can help these communities that need green spaces the most. The proposal dictates the cash in lieu fee money goes to affordable housing projects. Lower-income communities are more affected by climate change, and the locations of low-income neighborhoods usually experience more air and water pollution. Green spaces and solar energy are more attractive to potential occupants and can lower energy bills.

Increased compliance. Instead of only certain buildings complying, there are many options so everyone can comply. For existing buildings, there were a lot of exemptions originally. Although the form of compliance may not be an up-front cost increase (such as buying into Xcel Renewable Connect), it does level the playing field for developers and building owners.

How the New Proposal Hurts Developers

More complexity. More options mean more complexity. The permitting process will take longer, and the city will have to navigate eight options forms, criteria and regulations. It is harder as a developer to understand all the options and benefits to your bottom line when there is such an extensive menu to choose from. For new construction, green roofs could provide a payback of six years, according to “The Benefits and Challenges of Green Roofs on Public and Commercial Buildings,” a May 2011 report from the U.S. General Services Administration. They also can increase your valuation by 11 percent and provide an extra amenity space, according to “The Monetary Value of the Soft Benefits of Green Roofs,” a report prepared for the Canada Mortgage and Housing Corp. The task force cost analysis is only accounting for energy savings and doesn’t provide more data and information to help developers make the best informed decision.

Could reduce long-term cost savings. It seems that these new options are more affordable for developers, but the lower up-front costs of energy-efficiency programs will cause many developers to opt out of green roofs or solar. This means missing out on all of the benefits these options have to offer. By providing alternatives that seem less costly up front, developers and building owners may pay more overtime. A green roof can last two to three times longer than a traditional roof, which could mean saving the cost of several roof replacements, according to the GSA report. Also, green spaces retain tenants longer and reduce turnover, according to the Government of the District of Columbia Department of Energy & Environment.

Lack of incentives. The city of Denver also has the opportunity to provide incentives. Other cities like Washington, D.C., Chicago and New York City have been successful in incentivizing green roofs. The city should understand that green roofs and solar will save millions in storm-water management – a Green Roofs for Healthy Cities report estimates a saving of $23 million in reduced storm-water fees for Denver – and a reduction of health care costs due to heat related illness, biophilia design research finds. Denver has an opportunity to incentivize developers who are building green roofs to do fast-track permitting or direct or indirect economic incentives. The proposal may include a solar rebate program.

While there are more options for developers in the new proposal, by watering the original proposal down we are missing on many potential improvements to our community. If you have suggestions on how to improve the Green Roof Initiative email, or attend the June 25 City Council meeting at 1:30 pm in Room 391 of the City and County Building.

After this article is published, the task force could still make additional updates to the initiative.

You can find the original article in Colorado Real Estate Journal here.

Biosolar Roofs: The Ultimate Green Roof System

Green roofs are slowing taking over, with benefits ranging from better stormwater management to energy efficiency. And although the market and technology has fluctuated over the last decade, solar energy has become increasingly cheaper and more efficient, making it a perfect addition to any development project. Many developers opt for either a green roof or a solar panel array, or if they have both, often separate them in the design of the roof. But there are a lot of surprising benefits to having solar panels atop the vegetative platform on a green roof: enter the Biosolar roof.

A Biosolar roof is a green roof that combines the power of solar by building the array directly on top of a vegetative medium. You might be thinking this particular structure is too crowded, difficult to maintain, or too expensive. But in actuality, you are getting the best bang for your buck with this system, and the environmental benefits are great too.

Structurally speaking, a green roof makes a perfect ballast for the a-frames required to support a solar panel array. This allows installers to use the growing medium as a support for the panels without attaching the a-frames to the waterproofing membrane or the actual roof structure itself (further protecting the additional waterproofing benefits that a green roof provides)(1).

Vegetation also increases the efficiency of the the solar panels. Despite the amount of sunshine that may come with them, hot days do not help solar panels work better. Temperature plays a huge role in the energy production of a PV panel on a given day. And since vegetation cools the ambient temperature of a roof through evapotranspiration, placing the panels atop a green roof structure can make the payoff of your solar panel array much higher. Plants can also, in many cases, reduce the amount of airborne pollutants and dust, allowing the panels to absorb more sunlight (1).

Biosolar roofs also create a more diverse habitat through it’s unique stormwater runoff abilities. Due to the slanted nature of the PV arrays, a biosolar roof typically has three micro-habitats: one that is very moist due to the runoff of the panel, one that is dry and cool beneath the shade of a panel, and one that is ideal for growing sedum, a popular plant choice for green roofs. This level of micro-biodiversity is not often found in urban environments, so a Biosolar roof can help cultivate additional wildlife and nutrients for plants (2).

Although careful consideration for plant species, spacing of panels, and other factors should be considered in the design, a Biosolar roof can maximize the benefits of both solar energy production and vegetation at roof level.




What Do You Plant on a Colorado Green Roof?

With the new green roof ordinance in Denver, you might be seeing a lot more green towards the sky in the mile high city. But what sort of plants can survive the windy arid environments of a rooftop in a state like Colorado?

Sedum plants (more commonly known as stonecrops) are leaf succulents with up to 470 different species. Their flowers (which often have five petals) add a nice decorative element to green roofs that are installed for functionality and cost savings. Because their leaves retain water they are preferable to grass on green roofs, especially for modular systems (4). The EPA Building in Denver has an extensive modular green roof with a primarily sedum cover. Some of the variety of sedum plants used are Sedum acre, Sedum album, Sedum kamtchaticum, Sedum spurium ‘Dragon’s Blood’, Sedum spurium ‘John Creech’, and Sedum spurium ‘Red Carpet’ (3).

Other succulents, such as aloe vera, are also great plants to have on a green roof, especially one that is accessible. Many succulent plants have a unique and ornamental appearance, so they are perfect for green spaces while also perfect for the arid climate of Colorado. A study conducted by Colorado State University found that the succulent species overall as a group (compared to other species tested) maintained a healthy state five time longer than the next best species tested (herbaceous). Their revival rate was double that of others (1).

Beyond water retaining plants such as succulents and cacti, prairie grass such as Blue grama is also a popular choice for green roofs in Denver. The flagship REI store green roof features this particular grass, as well as a combination of shrubs and perennials (2). It also happens to be the official state grass of Colorado, and is often found in our beloved Rocky Mountains.

Last but certainly not least is our favorite plant selection for green roofs: food. Despite what you might assume, green roofs are great environments for planting vegetables, herbs, and various other edible goodies. Because of their highly contained environment, away from the garden variety of pests and plant diseases, they give plants an opportunity to thrive much like a container garden. Don’t believe us? Just ask The Gathering Place, Denver’s own daytime drop-in center for women and children experiencing homelessness. Their roof features a safe playground and garden that supplies some of the food used in the kitchen. The kids are often involved in the caretaking of the plants, making it educational and fun to boot (2).

Now that you know what sort of plants you can grow in Colorado, maybe you’re thinking a getting a green roof yourself!


  1. Extensive green roofs in Colorado: Plant... (PDF Download Available). Available from: [accessed Jun 07 2018].



The How Urban Heat Island Effect Impacts Public Health

Here at Sow Green, we have a pretty deep affection for green roofs. And it’s no wonder, they have so many benefits to both the private sector and the community that we can’t help but think they’re a pretty great solution to some of our biggest problems. One of those that we mention often is the Urban Heat Island (UHI) Effect. But what exactly IS a Urban Heat Island, and why are this so dangerous?

A Urban Heat Island is a metropolitan area that is significantly warmer than the surrounding rural/suburban areas due to urban development and human activity. Dark impervious surfaces, such as black rooftops, parking lots, and roads absorb higher levels of solar radiation, creating a pocket of heat and an increase in average temperatures. Urban areas also have much less vegetation, and therefore the level of evapotranspiration (the cooling of an area due to plant growth) has decreased (4). Urban Heat Islands have been associated with an increase in heat-related illness and a myriad of other public health issues.

The year 2017 was the third hottest year on record in the United States, and extreme heat is a leading cause of weather-related deaths, with over 1,000 people dying per year.

But not everyone has the same level if risk. According to the National Environmental Education foundation, children, the elderly, the sick, and people without access to air conditioning are at greater risk of heat-related illnesses. In the City of Denver alone, almost 50% of the population does not have air conditioning in their homes (3). People with mental illnesses such as depression or schizophrenia are also at a greater risk, since their medications may interfere with temperature regulation. Increases in death by suicide also correlate with high temperatures, as do crime rates and aggravated behavior (1,4).

The issue is not isolated to the United States, in fact people who live in developing countries are at an even greater risk. In 2015, Karachi, Pakistan lost at least 1,200 people to heat related illness, the majority of which were the elderly, sick and homeless. Government officials reportedly did not act, and Pakistan is due for another formidable summer this year (2).

Of the top 10 cities with the most intense summer urban heat islands, Denver ranks third only behind Las Vegas and Albuquerque. With average daily urban-rural temperature differences of around 5 degrees Fahrenheit, you can expect a hot day to get much hotter in the mile high city.

So what can we do to mitigate our Urban Heat Island? Green roofs reduce the amount of impervious surfaces by replacing black rooftops with vegetation that can cool the surrounding areas, while also cooling the building below. In addition to green roofs, cool or white roofs are also an economical method. Adding trees to a community can reduce ambient and surface temperatures by almost 10 degrees Fahrenheit. Protecting green spaces such as parks and community gardens can also have a positive impact on urban temperatures.

With better urban planning and policies that increase the development of green spaces in our cities (such as the new green roofs ordinance in Denver), we can reduce the public health risks of the Urban Heat Islands and create healthier, more just communities.