What was the revenue generated by the retiree exchange in 2020 
ome of it is connected to just fundamental capabilities, certainly on the climate side, property side, on cyber side. So a lot we're doing that we are very excited about in terms of the ability to help clients address issues critical to them but, heretofore, haven't been addressed in the way they need it to be. So a lot happening from that standpoint. But Eric, anything else you throw in on this?
Eric Andersen -- President
Yes. You just gave a great overview of it, Greg. But if you think about intellectual property and the new skills required there, you think about the new risk areas about renewable energy, about climate modeling capabilities that we need. You mentioned cyber. And certainly in our human capital business, trying to invest in how we do ESG at scale for clients. So there's a whole lot happening on the ground, as Christa said, that is supporting the growth that we're seeing and recognizing that we need to keep investing to make sure we keep growing.
Philip Michael Stefano -- Deutsche Bank AG -- Analyst
You know what thank you, good luck!
Operator
And the last question that we have in the queue for today is from Brian Meredith with UBS. Your line is now open.
Brian Robert Meredith -- UBS Investment Bank -- Analyst
Yes, thanks. Two quick questions here. First one, just curious, Christa, what's the revenue impact of the sale of the retirement exchange? It looks like you're continuing forward with that one.
Christa Davies -- Executive Vice President & Chief Financial Officer
Yes. So the revenue brand in 2020 for the retiree exchange was $176 million. It is predominantly a Q4 business, as you know well.
Brian Robert Meredith -- UBS Investment Bank -- Analyst
Great. And then second question, I'm just curious, as a part of this process that you're going on with Willis Towers Watson, you'd obviously identified a lot of cost synergies and expense potential savings from the transaction. I'm curious if you were able to identify any -- specifically for Aon,that you could see potentially here going forward to help with cost savings and efficiencies as you went through this process?
Gregory Clarence Case -- Chief Executive Officer & Executive Director
Brian, this is what we were alluding to and talked about before, and I'll come back -- Eric is going to jump in on this. Eric's led this integration in the last 16 months, and this has really been at the one foot level, literally as we engage and connect with colleagues around the world and with clients around the world. And we've seen an uncovered multiple growth opportunities, investment opportunities, expense opportunities, highly approachable to Aon specifically. And all those are going to be baked in as we move forward. This is back to the theme. We came in the March 2020 with exceptional capability strength. And what we've done over the last 16 months around integration is fundamental improvement of our platform. What's going to be the combination combined platform, but it absolutely is applicable to Aon. But Eric, you led this, what do you think?
Eric Andersen -- President
Yes, Greg, I think there's two buckets, right? I think on the revenue synergies, you're talking about the client value-creation model that we've been working on, otherwise are delivering in Aon United strategy about how do you bring the firm together. We're talking about how we're perfecting it. That was done in the context of the integration management planning. But also on the expense side, certainly real estate strategy, technology strategy, all the areas that you would think, having a fresh look with teams that were built specifically to try and challenge the status quo and really pressure test how can we do it better, how can we do it more efficiently? How do we leverage our Aon Business Services model in a way that we had really started during pre-Willis Towers Watson combination to really accelerate how we actually use that capability. I wouldn't necessarily call that last one new. I would just call it expanding what we've been building and really getting it embedded across the firm across th
ome of it is connected to just fundamental capabilities, certainly on the climate side, property side, on cyber side. So a lot we're doing that we are very excited about in terms of the ability to help clients address issues critical to them but, heretofore, haven't been addressed in the way they need it to be. So a lot happening from that standpoint. But Eric, anything else you throw in on this?
Eric Andersen -- President
Yes. You just gave a great overview of it, Greg. But if you think about intellectual property and the new skills required there, you think about the new risk areas about renewable energy, about climate modeling capabilities that we need. You mentioned cyber. And certainly in our human capital business, trying to invest in how we do ESG at scale for clients. So there's a whole lot happening on the ground, as Christa said, that is supporting the growth that we're seeing and recognizing that we need to keep investing to make sure we keep growing.
Philip Michael Stefano -- Deutsche Bank AG -- Analyst
You know what thank you, good luck!
Operator
And the last question that we have in the queue for today is from Brian Meredith with UBS. Your line is now open.
Brian Robert Meredith -- UBS Investment Bank -- Analyst
Yes, thanks. Two quick questions here. First one, just curious, Christa, what's the revenue impact of the sale of the retirement exchange? It looks like you're continuing forward with that one.
Christa Davies -- Executive Vice President & Chief Financial Officer
Yes. So the revenue brand in 2020 for the retiree exchange was $176 million. It is predominantly a Q4 business, as you know well.
Brian Robert Meredith -- UBS Investment Bank -- Analyst
Great. And then second question, I'm just curious, as a part of this process that you're going on with Willis Towers Watson, you'd obviously identified a lot of cost synergies and expense potential savings from the transaction. I'm curious if you were able to identify any -- specifically for Aon,that you could see potentially here going forward to help with cost savings and efficiencies as you went through this process?
Gregory Clarence Case -- Chief Executive Officer & Executive Director
 Brian, this is what we were alluding to and talked about before, and I'll come back -- Eric is going to jump in on this. Eric's led this integration in the last 16 months, and this has really been at the one foot level, literally as we engage and connect with colleagues around the world and with clients around the world. And we've seen an uncovered multiple growth opportunities, investment opportunities, expense opportunities, highly approachable to Aon specifically. And all those are going to be baked in as we move forward. This is back to the theme. We came in the March 2020 with exceptional capability strength. And what we've done over the last 16 months around integration is fundamental improvement of our platform. What's going to be the combination combined platform, but it absolutely is applicable to Aon. But Eric, you led this, what do you think?
Eric Andersen -- President
Yes, Greg, I think there's two buckets, right? I think on the revenue synergies, you're talking about the client value-creation model that we've been working on, otherwise are delivering in Aon United strategy about how do you bring the firm together. We're talking about how we're perfecting it. That was done in the context of the integration management planning. But also on the expense side, certainly real estate strategy, technology strategy, all the areas that you would think, having a fresh look with teams that were built specifically to try and challenge the status quo and really pressure test how can we do it better, how can we do it more efficiently? How do we leverage our Aon Business Services model in a way that we had really started during pre-Willis Towers Watson combination to really accelerate how we actually use that capability. I wouldn't necessarily call that last one new. I would just call it expanding what we've been building and really getting it embedded across the firm across th